Yes, that's one of the ways I've tried it.
If I put the 1st line at the beginning of the function interface.setlevel(), I get this error message: "...: attempt to index a nil value (global 'manager')".

If I put this command a few lines below (where it is only excuted when I change the level), then absolutely nothing happens if I actually (try to) change the level, also no error message in this case - it looks at if the setlevel() function would just be exited when this line is reached.
This LUA is really a crap ...