Their words.....

(B5) Are there certain persons who cannot legally receive or possess firearms and/or ammunition?

Yes, a person who –

(1) Has been convicted in any court of a crime punishable by imprisonment for a term exceeding 1 year
So it looks like you are correct.

There is an appeal process.
Do it and ask why you were denied.
Most times it is an error on their part, and works out, if you take the time to do it.