Reader 11 trustedFunction importDataObject fails

Last year wrote a small trustedFunction plugin for a UK banking group using importDataObject to allow users to automatically attach PDF factsheets from a remote shared folder to PDF letters of confirmation that are then emailed to the bank's customers.

The original target was XP and Reader 9.1 which worked AOK consistently.

The group has recently started a desktop upgrade to Win7 and Reader 11.0.18 and the plugin then fails to attach the factsheet PDFs.

I have tested using Reader 10.1.04 and the plugin works correctly - so I'm not sure exactly what version/patch breaks it.

However, the users can open and/or attach the factsheets PDF manual using Reader File > Open and  Add Attachment.

Removing Enable Protected Mode at startup resolves the plugin problem, but this is not an acceptable solution for obvious IT security reasons.

I have added both the path to the factsheets and the full file path for the factsheets to the Privileged Locations but this makes no difference.

One odd symptom of the problem is that once any user manually opens the remote factsheet, then the plugin works, but if they close Reader and restart it the plugin then fails to attach the remote file again.

Any help in finding a solution to this would be greatly appreciated...