In an ESXi 5.1 environment, the following warning will be observed in the 'Transport Selection' screen of the vRanger backup wizard when backing up vApps. This warning will appear even if there is Virtual Appliances are configured correctly. This warning does not effect the backup job and the Virtual Appliance will still be used.

Workaround: This warning does not effect the outcome of backup jobs and can be ignored. However if you do not want to see this warning please use backup groups instead of vApps.
Enhancement request CR15451 has been submitted to Development for consideration in a future release of vRanger.