User ID, Password or Date of Birth is incorrect...wife is having the same problem as me.
I remember I had to go onto the SE website and go to the security token portion of my profile because I had to input some strong line code into the app.. but I never had ANY problems with the User ID, Password, or DoB.. that really sounds like you might need to go onto your account make sure you imputed your DoB correctly.
SE and they told him his ban was due to RMT/Spamming etc. Apparently his account was compromised somehow and being used by a gold spammer to try and buy/sell.
That means he gave his info to one of the /shout'ers in one of the city states.. they aren't real gil sellers, but they act like em.. and then steal your info when you try to buy anything from them.