VSTO Doc deployment issue

Guys,

I have a Word doc created in Vis Studio t4office, 2005, and we are seeing this error when trying to run the release.

Why is this ? Is this something I can do in the code or is it down to machine policy ?

Thanks
Bob

Office document customization

The current .NET security policy does not permit the customization to run. Do not
change the security policy in your computer. The .NET security policy is controlled by
your administrator or the developer who wrote the customization. You can still edit and
save the document. Contact your administrator or the author of this document for further
assistance.