the only thing i can think of is, check once again if your settings (in your gmail acount) enable pop mail
when you sign into gmail, go to settings > Forwarding and POP > than down to POP Download, and make sure you checked either "Enable POP for all mail" or "Enable POP only for mail that arrives from now on"
(or go here for clearer instructions
http://gmail.google.com/support/bin/answer.py?answer=13273&topic=194)
IF you already have done that, than i do not know what the problem could be since your settings in plus seem correct.
(double check your password and email address though, maybe there's a mistake in one)