"Michael Chong" wrote:

> I have an (exe) executable program created in VB.NET 2003 that calls to a
> MFC DLL written in VC++.NET 2003. I always get an error msg
> "NullReferenceException: Object Reference Not Set to an Instance of an
> Object" when my exe calls the following codes:
>
> in VB.NET
>
> Declare Function test Lib "C:\Cyob\IOComm\Debug\IOComm.dll" _
> (ByVal a As Long, ByRef b As Integer) As Integer
>
> Dim did As Integer
> Dim ret As Integer
>
> ret = test(PortHnd, did) //ERROR: Object Reference Not Set to an
> Instance of an Object
>
>
> in VC++.NET
>
> extern "C" int APIENTRY test(HANDLE a, int *b)
> {
> *b=55; //ERROR: Object Reference Not Set to an Instance of an
> Object
> return 99;
> }
>
>
> Why is this happening? Any idea in solving such matter?
> Thanks in Advance
>
> Michael.
>
>