Hi Teuhc,
It might have something to do with the compiler options you use in VC++.
In Chapter 3 of the LabWindows/CVI Programmer Reference Manual, you find a section "Creating Object and Library Files in External Compilers for Use in LabWindows/CVI".
There is a list of options that are not to be used when building a library for CVI. If any of these options are used while building the library, it will lead to errors in CVI.
If you built the library yourself, please be shure that you don't use these options. If you didn't build it yourself, the only solution might be to use the shared library instead.
Regards,
Richard H.
National Instruments