A few questions:
1) Can you provide more detail about what you mean by "not fruitful"?
2) Did you use the PID vi provided in the FRC LabVIEW installation, or did you try to brew your own?
3) Are you bound and determined to use PID for shooter wheel speed control? Many teams have been quite successful using simpler control algorithms such as bang-bang.
4) Have you tried
searching the forums and reading some of the many threads on this topic?