Hey Ross,
I had some trouble with PocketMags in the past as well. It turned out my password was causing the problem. From memory it was deemed to complicated.
I contacted them and had the password cleared and then reset a simpler version and all was sweet. Their support staff are actually very helpful and quick to respond.
I certainly is annoying as the iPad doesn't tell you if it is your email OR the password that is the issue, it just says it can't access the server...
VMX42