TRX interface- FT 991 problem

[dl1daw]

My FT-991 is connected to my PC via the USB interface. I setup the 2 virtual ports (standard and enhanced) correctly. In the SWL comms- set-up window I selected the FT 991 and set the parameters of the ENHANCED COM Port  as DTR & RTS = ALWAYS OFF.
The FT 991 parameters are set as menue 033 CAR RTS = ENABLED. It works fine. I can SEE qrg, band, mode in SWL and can transmit CW BUT I cannot set the QRG from SWL neither  from the DX Announcement window nor from the TRX control window. However I can set the mode from these windows. Is this not strange?? I tried different configurations with different parameters but no success so far. Any experiences with FT-991 or hints? May I expect help and support?