Using dll from VB.Net 2005 based on C++ example

[mamu]

Hi All,

I need to use an existing dll in VB for which I have been given example sourcecode in C++. At first I thought it can't be that complicated, but after spending hours and hours trying to get this to work using trial and error (and reading around on the web), I am now at a point where I am out of ideas.

The C-example code for invoking the DLL is

typedef struct _ELS_CARD_SOCKET_HANDLE {
UCHAR uSocket;
UCHAR uFunction;
} ELS_CARD_SOCKET_HANDLE, *PELS_CARD_SOCKET_HANDLE;

extern ULONG ELS_GetCOMPortName(ELS_CARD_SOCKET_HANDLE hCardSock, LPTSTR lpComPortName, ULONG *lpComPortNameLength);

I turned this into

Public Structure ELS_CARD_SOCKET_HANDLE
Public uSocket As Byte
Public uFunction As Byte
End Structure

Public Declare Function ELS_GetCOMPortName Lib "elSerial.dll" (ByRef hCardSock As ELS_CARD_SOCKET_HANDLE, ByVal lpComPortName As String, ByRef lpComPortNameLength As Long) As Long

I have tried all sorts of variants for this without any success. I hope somebody can give me a clue what I am doing wrong. Thanks!