I've been trying to build a wrapper to use with the Authentec SDK for
fingerprint scanners. I am a .Net newbie and cannot get the interop dllimport
definition to work and return the result I expect.

Here is the .h function definition:
/////////////////////////////////////////////////////////////////////////////
//
// Function:    ATOpenSensor(TCHAR* pszStrSensorName, int16 iOpenMode)
//
// Purpose:        Open a sensor for use by the current service.
//                For typical systems with only 1 sensor attched, set param
//                "pStrSensorName" to NULL.
//
// Parameters:    pszStrSensorName:        Pointer to freindly name (NULL for only 1
sensor)
//                iOpenMode:            Either AT_SENSOR_OPEN_MODE_SHARED or
AT_SENSOR_OPEN_MODE_EXCLUSIVE
//
// Returns:   
//        AT_OK if the operation was successful.
//
//        Other: See error codes in ATInterface.h
//
/////////////////////////////////////////////////////////////////////////////
ATDLL_API AT_RESULT_CODE __stdcall ATOpenSensor(TCHAR* pszStrSensorName,
int16 iOpenMode);

I only have one sensor and I am trying to pass a null to it. Here is how I
defined it:

   <DllImport("ATSC63.dll", CallingConvention:=CallingConvention.StdCall, _
   CharSet:=CharSet.Ansi, EntryPoint:="ATOpenSensorA", SetLastError:=True)> _
   Public Shared Function ATOpenSensor(ByVal pszStrSensorName As IntPtr,
ByVal iAccessMode As Int16) As Integer
   End Function

And how I have called it:

           atResult = ATOpenSensor(IntPtr.Zero, 2)

I expect a result of zero and I get 125960192

I am using Visual Basic .Net...help!