I've just made a test listing suggestion to Business/Wholesale_Trade/General_Merchandise using the suggest URL link at the top of its page and it worked fine for me. Is that the method you were using?
I suggest that you try again and, if there are still problems, report them in this thread with a description of exactly what you were doing and the exact error message.
Proxy error messages when trying to contact an editor are not uncommon, though the message does usually get through. AOL systems engineers are aware of the problem.