The UIR editor automatically creates a .h file (with the same name, different extension, as the UIR file). The file includes the following warning:
/* WARNING: Do not add to, delete from, or otherwise modify the contents */
/* of this include file. */
You need to heed this warning.
The required CVI project design is to let the UIR have its own .h file. Create a new .h file (with a name different from the UIR file) for any user defined functions and constants, etc., and include it in your .c files.