Do you have ID running? Do you have a named document open?
Nothing is running. The only thing running is the Extendscript Toolkit CS5 and when I hit the "play" button he tries to open Indesign CS5 but shows that error message.
Your one liner is targeted at ID and without it running there is no app to query and no active document to return the name of. Try it as I suggested above.
nice, that works.
but one more problem.
another colleague uses Creative Suite Premium. And your solution works on her computer even without having ID and an active document running.
On the computer with the Master Collection your solution didn't work. I opend the toolkit and ID with an active document but still the chain icon was grey.
Can this be a profile problem?
Screenshot can be found below: