I am having a little difficulty getting something to work. 

I am trying to update a length across two forms. One is an inventory master and one a usage pane. 

After it is used I need deduct it out of the inventory master. 

I have tried the example of the Library which lead me to. 

Overall 

2 Forms Tally and Material_usage.

Length_field is Length of product in Tally

Remainder is Material Left over and to be re-written over original length field after Material_Usage is submitted.

Tag is my individual product key 

Length_field = Tally[Tag == input.TAG].Length_field

Remainder = Length_field

I get several syntax errors including Expecting "(" etc.

By trying to use the script builder  I will run the fetch dialog. However, the update will give me an error telling me to run the fetch dialog.

I am sure it is something simple. 

Thanks!