The Lighting Controller

It happens that my rack doesnt' work with a my specifics 4 channel dimmer (a dx 404 superlite). (This is the only machine i have that doesn't work with the rack).
In particular happen that when dimmer is connected with the rack, his dimmer led monitoring dmx signal goes flickering fast and continously and the apparatus doesn't work.
Otherwise with other standard dms consolle it's ok.
We did several test on that whith power usb and external power both: it seem that rack dmx signal is not "clear" ...but with "rumors".

We thought the rack should be broken, so they changed me it.
But whith the same results.
Mimmo

p.s.
Did you never had similar situation?
When the rack is working with usb or exernal power how should look the green led indicates dmx signal? (flickering or normally green on?)

We think that, if interface Rack has a dmx problem, all fixtures should see it.
FYI, interface Rack has same dmx signal than interfaces D512 & Remote.

The green led is flickering when there is a usb communication with the computer.