Hi,
The problem is that you NIDAQmx.h is probably not located in what your compiler considers the default include directories. There are two ways you could correct this. Instead of just typing NIDAQmx.h you could place the entire path after the include. Alternatively you could point your compiler to the proper location. The attached document explains how to get this working either way. Please let me know if you are still having problems, so I can stay on top of your issue.
When compiling a DAQmx ANSI C ExampleHave a great weekend,
Michael