DO11: Different User for Script Add in and Button Script?

Are the Script Add Ins executed with a different User?

The root problem for this question:
If I use my old Script embedded within a button.
Movie - Poster DL.dcf (16.3 KB)
Everything works without a problem on local or network drives.

With the new Version as Script Add In, everything works fine on local drives, but on network drives I get an Error "Die Datei konnte nicht beschrieben werden. (0x800a0bbc)" ["File could not be written"]. After some googeling it seems the root cause might be that the script has no permission to access the network path.

Any help or ideas how to further narrow it down are appreciated.

oups, I made a boo boo within the path creation, there was a faulty "\" that is ignored on local drives but, brings up the error on network drives.