Try it this way:
enter find mode  -->clear the pause check box. Do not specify any find criteria
Set FIeld [ContactByCompany::FullName ; Get ( AccountName ) ]
Set Error Capture [on]
Perform Find 
This is a method that allows the get function to evaluate--which doesn't happen inside a stored find request.
For more scripted find examples, see: Scripted Find Examples
Thanks as always for your help. I'm having an issue.
When I try to activate the following: Set Field [ContactByCompany::FullName ; Get ( AccountName )], it gives me the following error: An operator (e.g. +, -, *, ...) is expected here.
I checked the "Set Field" page on Filemaker.com, and it looks like what you suggested is what they suggest, but it still gives me the error.
What am I missing?
When Setting up Set Field, there are two Specify buttons that must be clicked. To get Set Field [Table::Field ; Expression], add set field to your script and click the first button (specify target field). Select Table::Field from the list of fields. Do not click the specify button next to the repetition box. Click OK to close this dialog box. Now click the lower specify button (calculated result) and create the expression to the right of the semicolon (;). Do not try to type in the semicolon.
That did it. Thanks again, Phil.