Iphone App "Invaild User"

Hello,

I recently installed the Live Support on my website to see what it's all about. I also downloaded the iphone app to accompany the service yet every attempt to sign in, reset passwords (read through help forums) I have yet been able to login successfully. Each time I receive the "Invaild User" and the file download process stops after the initial user name and password is entered.

What do I do?

Thanks in advanced,
john