does FM display the server - but no files? Could be the 'server.pem' issue.. that file could be missing or corrupt. You can copy the server.pem file from another machine
Thaks Markus, ther server.pem trick works fine
Make sure you don't have a keychain entry for that server where you may have logged in as a user that doesn't have access and saved the password.
Try this: hold the Option key down when you select the server from the Open Remote dialogue window. This should force you to re-authenticate even if you have a saved password/keychain for that server.