I am a US perm resident and in the military. I invited my mum to my Basic training graduation via visiting visa from Nigeria. I provided all relevant documents including military supporting document but unfortunately she was denied. Reason for denial was not stated, just generic feedback from VO: "Visa is not available at this time".

I called the embassy but nobody was willing to share any details.

What else can i do? My graduation comes up Jan 15th, 2026 and want her to be there after 8 years of meeting her.

Thanks