PDF Form Javascript field auto fill base on dropdown choice

Greetings,

I am creating a PDF but having some techincal issues.

Here is an image for reference.

There is a dropdown list named Materials. I would like the Material Price and the Line Total to be set to $58.00 when you've picked INCOMING MINIMUM LOAD 500.

So far i've tried this script to no avail, 

var f = this.getfield("Material");
switch(event.value){
case "INCOMING MINIMUM LOAD 500 ":
f.setMaterialPrice(58);

Any help would be greatly appreciated!