why can't i use gmail email for apple id on my phone

Im trying to set up a new apple id account (all texts and showing up on my phone, my ipad, my husbands phone). I set up a new email account on gmail. I set up new apple id using gmail account. Removed my phone from original account. All this done on my home computer. Now trying to reset info on my iphone and it wont let me use the gmail account I just set up!