Not being able to backup Hyper-V VM's in Windows 2012 cluster - Error: DPM encountered a retryable VSS error. (ID 30112 Details: VssError:The writer experienced a transient error. If the backup process is retried, the error may not reoccur. (0x800423F3)

I'm not being able to backup my VM's in DPM. I get the following error:

DPM encountered a retryable VSS error. (ID 30112 Details: VssError:The writer experienced a transient error.  If the backup process is retried,
the error may not reoccur.
 (0x800423F3))

My infrastructure is the following:

Hyper-V cluster host: 4 Windows 2012 Datacenter

Storage: CSV's on Dell EqualLogic connected thru iScsi

VM guests: Windows 2008 R2

VM guest additions: 6.2.9200.16433

Backup to disc or tape throws the same error

DPM Server: DPM 2012 SP1 (4.1.3408.0)

If i disable the backup checkbox on Integration services I'm able to backup the VM but it takes a Saved state backup of the VM even if on DPM is selected "Backup using child partition"

I tried different scenarios, like same all the same infrastructure mentioned above but instead of Hyper-V  cluster using stand alone and it works well.