Mr. Waller, the following names are listed on the National Parks Service web site (http://www.nps.gov./civilwar/soldiers-and-sailors-database.htm) which may or may not shed any light on the "A Roberts" for whom you are searching:

Alford Roberts, 8th Regiment, Virginia Calvary, Co. K (Film No. M 382, roll 47)

Alvin P. Roberts, 19 Regiment, Virginia Infantry, Co. H (Film No. M 382, roll 47)