An excellent moral; I believe that everyone here has at some point spent hours staring at their circuit and wondering why it doesn’t work. I also know that several users here (myself included) have fried entire panels as a result of failing to read the manuals thoroughly.
Show us how you wired it and what you want each device to do and maybe we can help you cross-reference what you set up against the wiring diagrams. In your original post, you mentioned the RTS being wired to trip an MS-5UD but you just now said that you’re using an MMF-300 with an MS-9200UDLS. There are some significant differences, however a key switch should be easy to wire as an input device to either a regular IDC or a monitor module.