K8000 with 3 K8005 cards

Hi There,
I have a K8000 running three K8005 cards. I have assigned them (the k8005’s) adresses 0,1 and 2. Individually, (i.e. not changing the address or wiring, just powering of the other 2) each of the motors work perfectly. In fact, they work perfectly in ANY combination of two K8005 cards. However, as soon as I add the third card (which can be any of the tree) the other two stop working. It seems as if the I2C bus is “flooded” or something like that. Any one with ideas?

Thanks in advance,