RP-405 MKII Relay Pack : Has DMX issues

The device has some issue with DMX. When I chose it to respond to a certain DMX address, say channel 100, it will only work correctly DMX channel one is not zero. When it is zero, and I set channel 100, the device starts to erratically switch on and off (tens of times on and off in 1 sec) which can't be good for either the switchpack nor the devices behind it!). While it's possible to work around this by making sure channel one is always set, it is a burden. This occurs even on short DMX links that are properly terminated, and I have several DMX controllers, including a USB one, and it responds to all the controllers in the same way. It's also the only device I have that seems not compatible.

The device itself is very sturdy and looks good, so other than the DMX issues it is of good quality.