Calling a FreeBASIC-DLL from VB

Hi,

I'm currently trying to write a DLL in FreeBASIC for calling from VB.
However, VB seems to load the DLL but cannot find my exported procedure
whatever I try.

This is my FB source (VBTest.bas):

DECLARE FUNCTION AddNumbers STDCALL ( _
   BYVAL operand1 AS INTEGER, BYVAL operand2 AS INTEGER ) _
   AS INTEGER

FUNCTION AddNumbers STDCALL ( _
   BYVAL operand1 AS INTEGER, BYVAL operand2 AS INTEGER ) _
   AS INTEGER EXPORT
   RETURN operand1 + operand2
END FUNCTION

Compilation using
fbc.exe -dll -export VBTest.bas
results in a file VBTest.dll.

Then my VB code:

Declare Function AddNumbers _
  Lib "VBTest.dll" _
  (ByVal operand1 As Long, ByVal operand2 As Long) _
  As Long

Sub main()
Debug.Print AddNumbers(1, 2)
End Sub

This fails with an error message saying that AddNumbers() cannot be found
in VBTest.dll. Obviously this is a correct error description because when
I
try this:

Sub main()
Dim hLib&, l&
hLib = LoadLibrary("VBTest.dll")
  If hLib Then
  l = GetProcAddress(hLib, "AddNumbers")
  FreeLibrary hLib
  End If
End Sub

then LoadLibrary() succeeds but GetProcAddress() returns 0.

I tried some variations like using an ALIAS clause but none of them
helped.
Anybody knows what I'm doing wrong here?

Any help much appreciated.

Wolfgang