Incomplete or lost Confederate service records are not that uncommon, especially in the Trans-Mississippi Department. The State Pension Board understood this problem, and could and did approve pension applications supported by sworn statements by the veteran's former officers and fellow soldiers, affirming that the veteran served in such and such a command, and that he left the service under honorable conditions. You can order a copy of the pension application file to see just what proof of service was presented. Absent an official service record document, I'll bet you find affidavits from his former comrades. This is quite common in Arkansas Confederate pension applications. A man's word counted for something in those days.