Hello,
Please, first could you telle me what is the version of NI-VISION you use and the IDE that you use to developp in C ?
Second, are you sure that you have installed the support for C/C++ languages during the installation of NI-VISION ?
On my system I have NI-VISION 8.2.1 and the Include files are loctaed in : C:\Program Files\National Instruments\Vision\Include and are named nivision.h and NIVisionH.DLL.
Regards
Pierre R...
Certified LabVIEW Developer