May sure you have the info set up correctly, such as the pool address and worker credentials. For me, that is one of main reasons my S1 would not mine. Also, make sure that the pool itself is posting the proper information or is being maintained properly if you are mining a new coin or on a less than professionally run pool.
Not sure if op has the s-1 or the s-2 . But pool settings need to be correct in either case.