colorfabb XT-CF20 - no extrusion

[SKDesign 0]

Hi,

I 've to print something for my client with the carbon filament XT-CF20 from colorfabb. This is my first print with this material ever and it just doesn't work.

I'm  printing with the UM2+ and for this material I got a 0.5 mm nozzle made of stainless steel.
So I change the material and the extruder pulls the XT-CF20 actually quite normal. The nozzle has 250°C and the material comes out of the nozzle as fast as normal, so I press ready.

But when I start printing, nothing comes out of the nozzle. I just don't understand why?

I pulled the material already 3x in and out and always exactly the same: while changeing the material it works, when I want to print it doesn't. Every other material works fine.

I hope anybody got a tip for me.
Any idea?

Thanks!

Simon