GoSMS - How to get notifications on lock screen

[itsdavetime]

I have the Samsung Galaxy S4 and have the lock screen enabled with a passcode. When the phone is locked, I don't receive the pop-up notification of an incoming sms. It works fine when the phone is unlocked, just not when it's locked. I've tried Handcent as well and have the same issue.

Does anyone know how to resolve this with Go SMS?

Thanks