CSLA error on Fetch data

Hi,

When i want to fetch record from CSLA it's giving error , we are using CSLA version 1 with window 7, 

please help me.

ExceptionSource: Csla: DataPortalException: DataPortal.Fetch failed ()
ExceptionDetail: Csla.DataPortalException: DataPortal.Fetch failed () ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Csla.Server.CallMethodException..ctor(String message, Exception ex) in C:\Tools\CSLA\csla20cs\Csla\DataPortal\Server\CallMethodException.cs:line 44
at Csla.MethodCaller.CallMethod(Object obj, MethodInfo info, Object[] parameters) in C:\Tools\CSLA\csla20cs\Csla\DataPortal\MethodCaller.cs:line 118
at Csla.Server.SimpleDataPortal.Fetch(Type objectType, Object criteria, DataPortalContext context) in C:\Tools\CSLA\csla20cs\Csla\DataPortal\Server\SimpleDataPortal.cs:line 109
--- End of inner exception stack trace ---
at Csla.DataPortal.Fetch(Type objectType, Object criteria) in C:\Tools\CSLA\csla20cs\Csla\DataPortal\Client\DataPortal.cs:line 192
at Csla.DataPortal.Fetch[T](Object criteria) in C:\Tools\CSLA\csla20cs\Csla\DataPortal\Client\DataPortal.cs:line 140

Thanks,

Vivek