Gradebook

I'm new to moodle and downloaded moodle 2.0 for OS 10.5.X Leopard. So far moodle has been great but I've hit a brick wall with entering and viewing grades. When I go to a specific assignment and try to enter a grade either manually or using quick-grade moodle doesn't save the grade I entered. Also on the Admin screen under the specific courses, when I click on the "Grades" icon and link another window pops up but it's completely blank. So, I don't know if this is a bug or something I'm doing wrong. Can anyone help with this?

thanks