Thousands of Confederate soldiers are not found in the Compiled Service Records files by their units. After years of sorting these cards into these unit files, the U.S. War Department clerks got tired of doing them and just put what was left into a new file. This file, in something resembling alphabetical order but not indexed at all, is called Unfiled Papers & Slips at the National Archives (RG 109, Microcopy M347, 442 rolls).
Only the National Archives has the complete run (I may be wrong here). The man you are seeking will probably be in there.
A friend of mine doing a unit history of the GA Troup Artillery told me about this massive file years ago. He found something like 25 guys he could not find in that unit's CSR rolls.
Greg Biggs