How do you add or change your e-mail login to facebook?

I have already gone to the account and then account settings where it asks to remove/add an e-mail. Every time I write the new e-mail it asks for my pword and then comes up with a box saying "please enter a valid e-mail address"!!! I have tried it for two days to no avail. Someone please help, what is the problem? My new e-mail works as I am getting mail in it....it is just one of those info@......com type of e-mails. My old one was an aol account. I wasn't sure if it was because I sign in with the aol one?