Don't see how upgrading from Filemaker 7 to 10 would change that behavior. Even older versions of filemaker worked as you are expecting set field to work here.
If these are two different database files linked via relationship, you might want to open Manage | External Data sources... and make sure that your relationship correctly links to the file you expect it to.
Are you using a Commit script step after the Set Field? Do you have access to FM Advanced, to run the Script Debugger and Data Viewer?
I agree, I don't understand how it is having problems. We are not using a Commit Script after the Set Field.
New update, we have run across two more databases that are having the same problem, but both of those are using a Copy from database A and then Paste into database B. These worked well in FM7 and now do not work in FM10...
Whew I'm stumped! Still working through it though.....
We do not have FM Advanced, but are considering it now. Would this possible tell us the problem?
Ok new update about what is going on.
IF the script is running and finds only one record, the script works fine. If there are two or more records, the SET FIELD and COPY/PASTE features are not working..... boy this sounds strange.....
So in my script, if there are two or more records it will not COPY the summary field, but if there is one record, it will COPY it.
With out examining your file or seeing a post of your script, it's pretty hard to see what might have gone wrong. Did you check the external data sources?
Copy and Paste are not the best approach here except for a very small handful of exceptions. One common gotcha with copy and paste steps is that they silently fail if the targeted field is not present on the current layout at the time the script executes. You can use parameters and variables to move data instead of copy/paste in almost all situations and these steps will not have this limitation.