Connect IIS virtual drive to FSX

I have connected the fsx drive to the ec2 instance and can view files through the windows explorer. I can not get IIS to serve files from the drive. I have added the virtual drive and can browse to it under IIS but when I test the "connect as..." setting it fails with message:

The path does not exist or environment variables in the path could not be expanded to verify whether it exists.

I have tried the EC2 admin user I have tried the active directory admin user(admin@activedirectoryxxxxxx.com) and of courset the IIS passthrough user. I have added everyone to a subfolder in the fsx drive. And tried adding various users to the permissions. Why cant iis find the fsx drive?