Restore grid from hardware appliance to vNIOS

[#1]

I'm trying to setup the VMware testing environment including the customer data for testing my scripts. I've made a backup from the customer's grid (hardware appliance, version 6.6) and now trying to restore it to vNIOS environment (also version 6.6) via Web UI. I get error: this backup file cannot be restored on this system. Since the version is the same and file is for sure not corrupt, what else can go wrong with my approach? Is it really not possible to play with it on vNIOS?
 

[#2]

Something was wrong with the file... I've done backup one more time and then restore on vNIOS run through without any problems. So I understand the world again... :-)