So some issues come to mind. First is get rid of the LMR400.
How is your CDM programmed. TX radio should be programmed for 462.625 TX And RX. RX radio should be programmed for 467.625 TX and RX. You cannot program a radio for TX only so i assume something is amis on the CDM. with a mic on the CDM you should be able to TX to your HT with no issues, and then recieve you HT on the RX radio with all the RICK unplugged. The rick is pretty basic and the description you mention looks like programming.
Also where is antenna located ? away from equipment I assume ?
