iTunes and Google contacts sync problem

Hello,

I want to transfer my iPhone 3GS (iOS 3.1.3 & Built version 7E18) contacts with to my Google Contacts using iTunes 11.0.4.4 (my computer OS is windows 7).

However, when I choose Google Contacts from the drop down menu under Info tab of iTunes & enter my Google account credentials, it rejects my password, although the password is correct.

I think there is a setting in Gmail which allows iTunes to sync with that.

Link https://www.google.com/accounts/DisplayUnlockCaptcha didn’t work too.

Can anybody guide me in this regard?

With thanks