Rems camscope, not transmitting image over wireless

[masterx81]

Hi!
I have a rems camscope (an endoscope camera with detachable display module) that not send the image when phisically disconnected from the camera gun.
Afaik it transmit in the 2.4hhz band. There is a way to see if is failed the transmitter unit or the receiver unit?
The receiver unit have 4 channel to select, but i not get any image in any of them. I think that the channels are here to match the monitor with different camera guns, but i've not see any way to set che channel on the camera body.
I not have anything that can measure an "over ghz" frequency.
Any ideas?