Downwards OS compatibility of applescript 'tells' in xCode project?

Hi forum,

I am working on a larger project, mostly Obj-C, but with some AppleScript for interaction with other Applications.
The applications is working fine when run under 10.4, but as soon as I try to run it under 10.3 it fails.

The Obj-C part is working regardlessly on both OSes and the most parts of the AppleScript too - I managed to find out that the non working parts are the calls to other applications (tell statements).
Why? Is there a switch I forgot to set for downwards compatibility of these Applescript parts?

here’s an example:


	tell application "Safari" to tell document 1 to set theURL to URL

many thanks for your help in advance,

Dominik