the file could be rejected due to the file type, file/options/dcc/folders and under the dcc ignore area do you see that file type listed under those to not ignore? On some networks certain file types also need to be allowed (/dccallow +nickname) In file/options/general/lock do you have gets disabled? Did you check to see if the sender was put on ignore? (alt b, control) Did the sender send you a msg wanting you to accept by dccserver on a certain port and you didnt enable that? Did you look in your status window for any msg describing the reject reason?
It is really NOT a good idea to set autoaccept, you are taking a big enuf risk downloading from strangers to begin without saying sure, anyone send me anything you want. Course, by accepting from strangers you're pretty much doing that anyway, but at least take the time to look at the file type, who is sending it, and cross your fingers before you say yes. Far from a safety guarantee, but at least you keep the option of refusing it.