Assignment

Hi can anyone help? i am using the assignment tool and have worked out how to change from % to Pass, Merit, Distinction howeverwhen I mark a students piece of work it at a pass it notes this and then has a final grade column of a fail? I think what is happening is that we also have a forum, and it is trying to average the marks out between the two, but the forum is not a graded item, am i missing something?

thanks

J