i have an error ( System.InvalidCastException: Unable to cast object of type 'AccountProxy' to type 'System.String'.) when i did this code

1. i mapped the tables( Account,AccountString,EventData,...) of the the database opengts ( open source)

2. i have this error when i called a function from EventData.cs

   IQuery query = session.CreateQuery("FROM Eventdata"); IList pets = query.List(); return pets;

the Stack Trace:

[InvalidCastException: Impossible d'effectuer un cast d'un objet de type 'AccountProxy' en type 'System.String'.]
   (Object , Object[] , SetterCallback ) +431
   NHibernate.Bytecode.Lightweight.AccessOptimizer.SetPropertyValues(Object target, Object[] values) +20
   NHibernate.Tuple.Component.PocoComponentTuplizer.SetPropertyValues(Object component, Object[] values) +49
   NHibernate.Type.ComponentType.SetPropertyValues(Object component, Object[] values, EntityMode entityMode) +34
   NHibernate.Type.ComponentType.ResolveIdentifier(Object value, ISessionImplementor session, Object owner) +150
   NHibernate.Type.ComponentType.NullSafeGet(IDataReader rs, String[] names, ISessionImplementor session, Object owner) +42
   NHibernate.Loader.Loader.GetKeyFromResultSet(Int32 i, IEntityPersister persister, Object id, IDataReader rs, ISessionImplementor session) +93
   NHibernate.Loader.Loader.GetRowFromResultSet(IDataReader resultSet, ISessionImplementor session, QueryParameters queryParameters, LockMode[] lockModeArray, EntityKey optionalObjectKey, IList hydratedObjects, EntityKey[] keys, Boolean returnProxies) +92
   NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +675
   NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +129
   NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) +116

[GenericADOException: could not execute query
[ select eventdata0_.deviceID as deviceID5_, eventdata0_.timestamp as timestamp5_, eventdata0_.statusCode as statusCode5_, eventdata0_.accountID as accountID5_, eventdata0_.latitude as latitude5_, eventdata0_.longitude as longitude5_, eventdata0_.gpsAge as gpsAge5_, eventdata0_.speedKPH as speedKPH5_, eventdata0_.heading as heading5_, eventdata0_.altitude as altitude5_, eventdata0_.transportID as transpo11_5_, eventdata0_.inputMask as inputMask5_, eventdata0_.outputMask as outputMask5_, eventdata0_.address as address5_, eventdata0_.DataSource as DataSource5_, eventdata0_.rawdata as rawdata5_, eventdata0_.distanceKM as distanceKM5_, eventdata0_.odometerKM as odometerKM5_, eventdata0_.geozoneIndex as geozone19_5_, eventdata0_.geozoneID as geozoneID5_, eventdata0_.creationTime as creatio21_5_ from eventdata eventdata0_ ]
[SQL: select eventdata0_.deviceID as deviceID5_, eventdata0_.timestamp as timestamp5_, eventdata0_.statusCode as statusCode5_, eventdata0_.accountID as accountID5_, eventdata0_.latitude as latitude5_, eventdata0_.longitude as longitude5_, eventdata0_.gpsAge as gpsAge5_, eventdata0_.speedKPH as speedKPH5_, eventdata0_.heading as heading5_, eventdata0_.altitude as altitude5_, eventdata0_.transportID as transpo11_5_, eventdata0_.inputMask as inputMask5_, eventdata0_.outputMask as outputMask5_, eventdata0_.address as address5_, eventdata0_.DataSource as DataSource5_, eventdata0_.rawdata as rawdata5_, eventdata0_.distanceKM as distanceKM5_, eventdata0_.odometerKM as odometerKM5_, eventdata0_.geozoneIndex as geozone19_5_, eventdata0_.geozoneID as geozoneID5_, eventdata0_.creationTime as creatio21_5_ from eventdata eventdata0_]]
   NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) +213
   NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters) +18
   NHibernate.Loader.Loader.List(ISessionImplementor session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes) +79
   NHibernate.Hql.Ast.ANTLR.Loader.QueryLoader.List(ISessionImplementor session, QueryParameters queryParameters) +51
   NHibernate.Hql.Ast.ANTLR.QueryTranslatorImpl.List(ISessionImplementor session, QueryParameters queryParameters) +231
   NHibernate.Engine.Query.HQLQueryPlan.PerformList(QueryParameters queryParameters, ISessionImplementor session, IList results) +369
   NHibernate.Impl.SessionImpl.List(String query, QueryParameters queryParameters, IList results) +317
   NHibernate.Impl.SessionImpl.List(String query, QueryParameters parameters) +282
   NHibernate.Impl.QueryImpl.List() +163
   DATA1.EventdataExtensions.GetEventdata() in C:\Users\HP\Desktop\our_project\DATA1\Queries\Eventdata.cs:33
   MvcApplication7.Controllers.HistoriqueController.Index() in C:\Users\HP\Desktop\our_project\MvcApplication7\Controllers\HistoriqueController.cs:17
   lambda_method(Closure , ControllerBase , Object[] ) +62
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() +55
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +263
   System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +191
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
   System.Web.Mvc.Controller.ExecuteCore() +116
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97
   System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
   System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
   System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50
   System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7
   System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8841105
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

Any suggestions? how can correct this error

Data entity class (outtake from comment):

public class MyClass
    {
        public virtual string DeviceID { get; set; }
        public virtual int Timestamp { get; set; }
        public virtual string Account { get; set; }
        public virtual int StatusCode { get; set; }
        public virtual double Latitude { get; set; }
        public virtual double Longitude { get; set; }
        public virtual int GpsAge { get; set; }
        public virtual double SpeedKPH { get; set; }
        public virtual double Heading { get; set; }

        public override bool Equals(object obj)
        {
            return true;
        }

        public override int GetHashCode()
        {
            return 0;
        }


    }