Copy and paste script steps, like the script steps that begin with the keyword "Insert" do nothing but return an error code if the field that reference is not present on the current layout. In addition to that, The Copy step destroys any data the user may have previously copied to the clipboard. This irritates and confuses users and is completely unnecessary as there are other ways to move data around that do not require the use of copy/paste to do so.
Also wlidcards like * are treated as simple text, not a wild card in such an If script step. (Wildcards only work in Find mode when performing a find. So your above script will only copy data if the exact quoted text, (One space followed by an asterisk followed by another space), is the total value of the field at the time the script trigger is tripped.
But you can open field options for CMA Resit Compensation Copy and define an auto-enter calculation with this expression:
CMA Resit Compensation
Just leave the "do not replace existing value" check box selected and you should get what you need without any scripting.
Thanks PhilModJunk; so simple and so quick.