Box 2A of 2016 Form CSA 1099R, shows "Unknown". I retired on Fed Civil Serv. Disability from SSA over 20 yrs ago. No idea when adj to be made.

Box 2A of 2016 Form CSA 1099R, shows "Unknown". I retired on Fed Civil Serv. Disability from SSA over 20 yrs ago. No idea when adj to be made. Please help.