Possibly because yiu have long path name or spaces in gcName.
First try just:
use (gcName)
If it is OK, then try:
use (gcName) alias screendata



>>>>>>>>>>>>>>>>> your question below >>>>>>>>>>>>>
I must be in the forest, because I can't see a tree.
I need some fresh thinking.
The following code produces a "File is in use" error.

----start code
select 0
use &gcName alias screendata
----end code

----given
1. It's in a VFP 5.0 .app
2. gcName contains a valid name of a .scx file complete with path.
3. the .scx file is not in use.
4. the alias "screendata" is not in use.
5. when the "use" command is copied to the command window and executed,
it works without complaining.

Why would this command return "file is in use" error when run in the program
but not when run in the command window?

I appreciate any thoughts y'all might have.
Thanks
Bob