ID and password

I can't get signed in to watch tv online, I have my ID and password already but it doesn't work for online tv. I was told I could watch already since I am signed up for tv and cable - before the installation - but the app won't accept my email and password. It says I can't even have a "@" in my ID. AT@T help page says this ID will work with all my apps, is the "TV Online" a different animal that has to be signed "UP" for instead of signed "IN" to? I think the internet is Viasat , is that not AT&T?