Failure at NARA

Last month I sent a request to NARA to obtain John Reid Smith's military file only to be told they are unable to locate him. I'm not sure how he has a military headstone but the National Archives have no record of him. Can someone shed some light on this for me?

Brickwall - John Reid Smith

Currently I do not know the names of John Reid Smith's parents or siblings. I also don't know for sure if he was born in Kentucky and if so where. I am assuming he was born in KY because of his enrollment in the military.

I wrote to the Illinois State Archives to retrieve John and Polly's marriage certificate but they do not have it on file. I also contacted White County Illinois genealogists and they are unable to locate a copy as well. Below is John's profile to date.