Outlook 2007 Add-in Problem in Vista

Hi,

I have developed a VSTO SE Outlook 2007 add-in with Visual Studio 2005.
I used the default setup project to create the setup files.
Upon installation, the Add-in works fine in all operating systems, except Windows Vista
The add-in doesn't load. To check, when I view it in the ‘Tools->Trust center->Add ins->Com Add-in’ of Outlook 2007, the message it gives is "Load Behavior: Not loaded.The Managed Add-in Loader failed to initialize"
I have also created a project called "SetSecurity" to use Caspol to give FullTrust permissions for all the assemblies.

In my SetSecurity Project, in a file called CaspolSecurityPolicyCreator.cs, I have the following code:
// Add the solution code group. Grant no permission at this level.
string arguments = policyLevel + " -q -ag " + parentCodeGroup + " -url \"" + solutionInstallationUrl + "\" Nothing -n \"" + solutionCodeGroupName + "\" -d \"" + solutionCodeGroupDescription + "\"";

As it says, not granting trust at this, is that the problem?
If so how to grant trust at this level too?

Any ideas/suggestions from anyone on how to get it to work under Vista?

You might get more information on the load failure by adding an environment variable VSTO_SUPPRESSDISPLAYALERTS and setting its value to 0 - on XP this gives full error messages for failures of Add-ins to load.