I use this:

public IQueryable<MaterialsView> FindAllMaterials()
{
var materials = from m in db.Materials
                join Mt in db.MeasurementTypes on m.MeasurementTypeId
                       equals Mt.Id
                            select new MaterialsView {
                                MatId =  m.Mat_Name,
                                MesName =  Mt.Name, 
                                 MesType = m.Mat_Type };
            return materials;
}

It gives me the following errors:

1. The type or namespace name MaterialsView could not be found (are you missing a using directive or an assembly reference?)

2. Cannot implicitly convert type System.Collections.Generic.IEnumerable<MaterialsView> to System.Linq.IQueryable<MaterialsView>. An explicit conversion exists (are you missing a cast?)

3. The type arguments for method System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>) cannot be inferred from the usage. Try specifying the type arguments explicitly.

I have googled it and found this SO question but it doesn't help.

What's wrong?