Ok guys. I need some help with my homework.

We are covering javascript in my web languages class and I'm stuck on a problem that I need a second set of eyes.

Scenario:

I have an order form with three drop down boxes with 4 products. The user needs to be able to select the items they want to purchase and then calculate the totals dynamically. I've been using the "onselect" option. I'm missing something somewhere and I've messed with it long enough. Could you guys give me a hand?

Here is the link.

http://test.flfchurch.com/unit_6/ordercalc.html