The DM10A is an RF unit. The CM11A responds to commands on the power line only. Therefore, you cannot receive the RF commands that the DM10A sends out. The CM15, I believe is both a power line and an RF interface.
Please be aware that X10 has two standards, the home control and the security. The data formats are somewhat different. Some pieces of equipment can see the home control data, but ignores the security data. For example, my people have added a TM751 to the system thinking that this would add RF. However, TM751 filters the data and only passes the home control data that matches the house code that it is set to. I believe that your DM10 is sending the security format.