Video Output Decklink 4K Extreme clipping

Fusion 7.6 build 0
PC Workstation: HP Z800
Output card: Decklink 4K Extreme
Blackmagic Desktop Video 10.3.4
Windows 7 64bit.
Global I/O Setting Blackmagic: HD 1080i 50 10bit RGB
also tried: (HD 1080p 25 10bit RGB)

The HDSDI output from decklink 4K Extreme to monitor is clipping (16-235).
The HDSDI waveform monitor just show a signal between (16-235)
Inside Fusion the signal is (0-255), everything is OK
The Source Gamma Space setting (Loader) have no effect.
So colorgrading is not possible.

What could be causing this?
Thanks for the help,
Wolfdieter

Sorry, something i forget:
I use the same configuration with Resolve,
here everthing is working fine.