Have you tried setting it up in your Settings app first? It needs that done, else it won't run correctly.
If you've set it up and it still doesn't work, may I suggest you go back to Cydia, uninstall it and then re-install it again.
That's all I can think of - because I do not have this problem (my PKGBackup works/worked flawlessly). If all else fails, you,could contact the developer...?
Marilyn