XL97: "Bad DLL Calling Convention" When Running a Macro

• Microsoft Excel 97 for Windows

SYMPTOMS

When you run a Visual Basic for Applications macro in Microsoft Excel 97, you may receive the following error message:

   Run-time error '49':
   Bad DLL calling convention

CAUSE

This problem may occur when all of the following conditions are true:

• The Visual Basic macro code contains one or more Declare Function statements.

      -and-
  

• One of the Declare Function statements refers to a function in a dynamic-link library file (DLL) that uses the _cdecl calling convention.

      -and-
  

• Within the code, you make a call to the declared function.

MORE INFORMATION

DLLs in Microsoft Windows support two main calling conventions: _cdecl and _stdcall. Most 32-bit DLLs that are included with Microsoft Windows 95 and Microsoft Windows NT support the _stdcall calling convention; the _cdecl calling convention is generally used by older DLLs.

If a DLL supports only the _cdecl calling convention, you cannot call functions in that DLL from a Visual Basic macro in Microsoft Excel 97. For example, if your code includes the following function declaration:

   Declare Function memcpy& Lib "Crtdll" (ByRef Dest&, ByVal Src&, _
       ByVal Count&)

NOTE: In earlier versions of Microsoft Excel, you can make calls to functions that use the _cdecl calling convention.