Weak contact between shell and infill

First let me thank you for your great product, the Zortax M200. I´ve had an Ultimaker2 before, but never get these great results, especially with ABS, than with the M200.
 
But now to my problem: It´s the same with all prints, independent of material (with Z-ABS and Z-Ultrat) and print settings (different layer-heights, fan-settings). The shell is not connected to the infill. During fracture tests the shell separates from the infill and the parts collapsing. Because there is no stress whitening (no white surfaces in the broken areas), I think there was never a contact between shell and infill.
 
Enclosed find an easy sample showing this problem.
 
 
Has anyone a solution or this problem?
 
 
Regards, 
 
 
Gerhard
 
 

Gonna print one right now.. I'll let you know.