Hi Peter,
please check the version of your form-properties. Here you could define the target-version of your PDF-File for adobe reader 8.0 oder some else.
General you should upgrade the adobe reader, because there are many security problems with older adobe reader Systems.
For a clean and secure system you should use adobe reader 10 or higher.
For "inline-debugging" you could popup a messagebox with uniq text, so you could check, if the script will be processed.
For any questions, ask me.
Regards,
Jeremia Girke