Remote module influenced by induction (I think...)

[FaneDuru]

I made an automation to drive a sliding gate. Everything analogue using two relays and two contactors. The gate is driven bay a gear motor 3x400V.
Recently I put a radio remote control module. The module itself worked good until I connected it to the existing scheme.
The module looks to be influenced by induction of the relays and contactors. I mean when I press a button of the remote control is should close a micro relay inside and it does that, but from time to time immediately after closing the micro relay is switched off or vice versa (it is closed when I try to switch it off).
I solved the influence of relays (12 V dc) putting a diode on their coil.
I also solved also the influence of contactors (230 V ac) using two capacitors of 100 micro. Everything worked perfect before I connected the 3x400V motor.
After motor connection the remote module is again influenced and gives errors in switching (on and off).
I also mention that the command (12 V dc ) uses a cable in a steel pipe and supply cable for 3x400 V motor is also in a different steel flexible tube. I use a supply source of 12V dc/3 A. The comsumption is less then 1 A...
What do you suggest to try in order to reduce the motor influence?

Thanks in advance!