Pixhawk CubeBlack 2.1 + SIK Radio V2 433MHz not transmitting

Hello guys,

I’ve been having trouble trying to get 433MHz telemetry to work. Currently on Arducopter 3.6.11, radio modules on SIK 2.0. Already made sure everything is matched in terms of setting of local and remote SIK radios.

However, they are not transmitting to one another (no flashing red). They are bound to each other though (solid green).

Please give me some inputs

I bought 6 different sets of SIK telemetry from different vendors on aliexpress and only 2 of them works ok. So maybe they just faulty. My common problems was also inverted wires, this one for transmission.