If your Call Uitlization is set to 100%, an agent would never get a call while they have an email. Having a call and an email would place them at 150% utilization, which isn't going to work. In your current setup, there is 1 call and 1 email waiting and an agent goes available, they will get the call, but as soon as they get an email, they will only be handling emails until all emails have been removed from their queue.
Try lowering your call utilization to 50% or less. Make sure you keep the max assigned at 1 though, especially if you go under 50%.
That should get you the results you are looking for. If not, then I would take a look at the ACD logs to determine the calculations used as George has suggested.