Rich:
I believe the source of your problem is that you are attempting to use a C++ DLL in LabWindows/CVI--which is an ANSI C compiler and does not support C++. The ampersand "&" used in this context signifies a variable passed by reference, which is not available in ANSI C. Furthermore, C++ DLLs usually use name mangling, which ANSI C does not support. Name mangling probably explains your link errors.
You can use the phrase extern "C" around the prototypes in a header file to disable C++ name mangling so the DLL can be used in ANSI C. However, this change would require you to re-build the DLL from source that you probably don't have. You can ask LabWindows/CVI to build an import library from the DLL and the source code, but LabWindows/CVI will not mangle the names in
the header file and thusly won't be able to find them in the DLL.
This doesn't leave many alternative that I can think of, especially if the API in the DLL uses call by reference. The best people to talk to would be ICQ; ask them if there exists an ANSI C API, and explain why this DLL won't work in ANSI C. You may also want to contact National Instruments technical support at 1-800-IEEE-488 or http://www.ni.com/support for other possible alternatives.
Best Regards,
Chris Wood
Applications Engineer
National Instruments