Dear Decodium Developer, I would like to report a reproducible issue with CAT control in Decodium 4. Configuration: Decodium 4 v1.0.498 Yaesu FT-991A microHAM microKEYER II DXLab Suite Commander (latest version) OmniRig Windows 10 The hardware and CAT interface have been verified with other software. WSJT-X CAT works correctly. Bidirectional frequency control works. PTT works. Audio modulation works normally. N1MM+ Works correctly through DXLab Commander. Problem 1 – DXLab Commander backend When "DXLab Commander" is selected as the radio interface in Decodium: Decodium correctly reads the radio frequency from Commander. Any frequency change made directly on the radio is immediately reflected in Decodium. However, when a frequency is selected or changed inside Decodium, Commander does not transfer this change to the radio. CAT communication appears to work only in one direction (Radio → Commander → Decodium). Problem 2 – OmniRig backend When "OmniRig" is selected: Bidirectional CAT frequency control works correctly. Pressing TUNE switches the FT-991A to transmit. However, there is no audio modulation during transmission. No transmit audio is generated by Decodium, although the audio configuration is correct. The same audio configuration works perfectly with WSJT-X. The microHAM microKEYER II configuration has been verified and works correctly with WSJT-X and N1MM+. Could you please verify whether these are known issues or if there is any recommended configuration for DXLab Commander and OmniRig with microHAM microKEYER II? Thank you very much for your support and for developing Decodium.