IIS application gets Access denied to UNC folder that has proper permissions

A customer of ours has given us 2 virtual machines and a shared folder on a different machine that I don't have access to. I want to access the shared folder from an IIS 7 application that runs on the virtual machines.

When I log onto the virtual machines I use the user "XXX\aaa".

The web application runs in its own App Pool and that App Pool has been given the Identity "XXX\aaa". I can modify the permissions on the shared folder and have added "XXX\aaa" as having full control of the shared folder.

The IIS application gets "Access to path \\sharded\folder is denied".

From either of the virtual machines, I can added folders and files to the shared drive. I can also do this with an console application.

However, if I create a shared folder on one of the virtual machines and point the other virtual machine to use the first, I am successful - even though "XXX\aaa" has not been added to the security. FYI: however, Administrators is in the security, but "Administrators" is not available on the shared folder. I presume "XXX\aaa" is part of the "Administrators" group and that is why it succeeds. I can't add "Administrators" to the shared folder, but I would assume that adding "XXX\aaa" would suffice.

I want to be able to go back to the customer and explain what needs to be done, but I don't have a clue!

Tags: IIS 7.0, IIS, Security