error: Undefined symbol DiscardAsyncTimer in *.obj

This picture describes my problem:

As suggested in "Linker error: Undefined symbol CRC referenced in .obj"

1. I have included the file asynctmr.h from CVI2013\toolslib\toolbox

2. You can verify that the *.h contains the function definition.

3. But still, building the project gives the error undefined symbol.

4. I tried browsing my *.prj, and indeed within my functions I do not see DiscardAsyncTimer. Why?