((Weight  *  0.417  +  Weight1  *  0.585  +  Weight2  *  0.75  +  Weight3  *  0.9  +  Weight4  *  0.916  +  Weight5  *  0.999)  /  20)

It works great in calculating the value I am looking for. For fields Weight, Weight1, Weight2, Weight3, Weight4, and Weight5 I am multiplying by a known number. I want to add field  Weight6 but the number that it is to be mutiplied in order to give me the value I am looking for changes. I added an additional field Fineness to enter the proper number to multiply Weight6 by in order to give me the value I need and added it to the formula. It looks like this:

((Weight  *  0.417  +  Weight1  *  0.585  +  Weight2  *  0.75  +  Weight3  *  0.9  +  Weight4  *  0.916  +  Weight5  *  0.999 + Weight6 * Fineness)  /  20)

When I enter anything into fineness on the form it does not provide an answer to the formula but if I leave the Fineness field blank it works perfectly. I am assuming I need to change the script to refer to the value entered into the Fineness field but after searching for hours and trying many different things I can not figure it out. I just started trying to make an application for the first time yesterday so I am sure it is just something basic that I have not learned yet. Anyone got an idea?

(In case anyone is curious I am using it to calculate how many troy ounces of pure gold you have if you buy different amounts of non pure gold. The numbers that go along with Weight(1-5) correspond with a common Karats (purity's) of gold. Sometimes you get items that are not the common and those are the ones I am entering in Weight6 and changing the field Fineness to whatever purity is actually is.)

Thanks in advance!