The situation:

The virtual infrastructure is built upon ESX 3.5 Update 1 Hosts. VCB Framework 1.1 and vRangerPro (with VCB Plugin will be installed on a dedicated physical server attached to an EMC SAN using iSCSI.

It has been my experience, that when the following tasks are performed in order, the installation will be successful:

1. Connect the iSCSI NICs to the SAN switch
2. Install and Configure the Microsoft iSCSI Initiator
3. Install PowerPath if the backup server has multiple connections (HBAs, iSCSI NICs, etc.) to the Storage LUNs.
4. Install vRangerPro
5. Install vRangerPro VCB Plugin
6. Install VCB Framework 1.1
7. Install .NET Framework 2.0 Service Pack 1
8. Test VCB backup job manually
9. Test vRanger backup with VCB plugin enabled

I hope these steps help you to realize a successful implmentation of vRanger and VCB.