Permissions on specific folder to write to

Hi All,

We are running an application on IIS 7 which has to output data to a specific (local) folder. The application is running anonymous auth. and the application pool is running with a service account which we created in AD.

When we set modify permission on the specific folder (d:\<appname>\output) for the service account directly, the output is writen to the folder without problems. When we use a security group where the service account belongs to, and we give modify permission to the groupit cannot be writen. No application error, no iis logs which gives me a push in the right direction :-(

Hope you can help me out because we want to use groups to set permissions, not directly on accounts.

Regards,

Mischa