Here's what happens:
1) I tap on the 'Email' icon. A 'Set Up Accounts' page comes up.
2) I tap on the 'Email Accounts' option and a 'Select email account to add.' page comes up.
3) I tap on 'Gmail' and it ask me to enter my existing gmail account.
4) I do so, and it says 'Attention Invalid credentials.' even though my gmail account name and password are specified correctly.