DPM 2012 R2 - Item Level Recovery error when Descending into a .VHDX only 2008 Server

I need to remove and reinstall my DPM 2012 R2 RU6.

Everything works fine. Then I tried the Item Level Recovery. On every 2008 Server I receive the same Error:

PM cannot browse the contents of the virtual machine on the protected computer xxx.xxx.ch. Item level recovery is not supported in the following scenarios.
1. The VHD contains a dynamic disk inside the guest OS.
2. The VHD has no volume.
3. HyperV role is not installed on DPM server.
4. Automatic mounting of volumes is disabled on the DPM server.

1) Try enabling automatic mounting of volumes using mountvol on the DPM server to preform item level recovery.
2) Otherwise perform a full restore of the virtual machine.

ID: 958
Details: Internal error code: 0x80990F4E

All this Hyper-V VHDX Server are on a 2012 R2 Cluster.

For Testing I have a Standalone HyperV Server. On this every 2008 Server works fine.

All 2012 Server works fine.

Any Idea.

Thanks in advanced for any Tip.

Roendi