Communication issues YL128-rs422 and Sik radio

Hello dear people.

I am running some sensors that require rs422 connection. I want to relay these signals threw the Sik radio, but it will not act on signals from the rs422-converter. I have tested that the signal source and rs422 converters is functioning. I have also tested that the Sik is working on another signal source. The two just dont dig each other. Nothing gets threw. I have a feeling that maybe the Sik desires more voltage on the peaks than the converter gives. I have been trying to find som detailed specs on the ttl-parts (or chip) of the Sik, but cant find any. Does anyone know the threasholds? Or does this problem seem familiar to someone that has already solved it perhaps?

Best Regards