Is your antenna the kind that threads on or just pushes on to the plug. If it threads on it may just be a pain to get the threading right. I wouldn't think that it would be the plug because we have a dollar store one in the living room and in the bedroom we have new ones that came out especially for the converter boxes.

Don't rely on me though, if the dang thing don't fit then it don't fit. Give it a good push though.