Hi, I have created a custom dialog UI, which contains two combobox with SQL server instance & on selection of one of SQLServer instance, another combobox has to be filled with name of Databases on that server instance. I am able to find filling combo with SQL server Instances I had written a similar CustomAction to fill the combobox with database names [CustomAction] public static ActionResult FillDatabases(Session xiSession) { xiSession.Log("Begin CustomAction"); xiSession.Log("Opening view"); View lView = xiSession.Database.OpenView("DELETE FROM ComboBox WHERE ComboBox.Property='DBNAME'"); lView.Execute(); lView = xiSession.Database.OpenView("SELECT * FROM ComboBox"); lView.Execute(); int Index = 1; //bool flag = false; try { Microsoft.SqlServer.Management.Smo.Server svr = new Microsoft.SqlServer.Management.Smo.Server(xiSession["DBSRVR"]); foreach (Microsoft.SqlServer.Management.Smo.Database db in svr.Databases ) { String dbName = db.Name; Record lRecord = xiSession.Database.CreateRecord(3); xiSession.Log("Setting record details"); lRecord.SetString(1, "DBNAME"); lRecord.SetInteger(2, Index); lRecord.SetString(3, db.Name); xiSession.Log("Adding record"); lView.Modify(ViewModifyMode.InsertTemporary, lRecord); ++Index; } } catch (Exception ex) { //logException(xiSession, ex); xiSession.Log(ex.Message ); } lView.Close(); xiSession.Log("Closing view"); lView.Close(); return ActionResult.Success; } I want to call these custom actions somewhat like shown below, <Binary Id="CustomActions.CA.dll" SourceFile="CustomActions.CA.dll" /> <CustomAction Id="FillServerInstances" BinaryKey="CustomActions.CA.dll" DllEntry="FillServerInstances" Execute="immediate" Return="check" /> <CustomAction Id="FillDatabases" BinaryKey="CustomActions.CA.dll" DllEntry="FillDatabases" Execute="immediate" Return="check" /> <InstallUISequence> <Custom Action="FillServerInstances" After="CostFinalize" /> <Custom Action="FillDatabases" After="FillServerInstances" /> </InstallUISequence> I need to show this Sqlserver selection custom dialog from another custom UI, in case user clicked on a pushbutton. Am I doing the right thing in the WiX code? Is there a better way in which combobox custom action fire only when user click on a pushbutton? "FillDatabases" custom action have to be fire whenever user select a new SQLServer instance. How do i do that? Thanks