Homematic Binding with YAHM

I set up YAHM and openHAB on the same Raspberry Pi.

Raspbian with openHAB got the IP address
YAHM on Raspberian got IP address

I set up openHAB and enabled the Homematic binding. OpenHAB got the things from YAHM and everything works.

But I got one problem.
I got a dimmer from Homematic. Now, if I change the level of this dimmer in openHAB, the light level changes immediately, and the slider in openHAB changes its position, everything correct.
But now, the slider jumps back to its initial position in openHAB without affecting the light.
After 2 to 3 seconds it jumps to its real position.

I don’t know why this is happening.

Did somebody experienced something like this?