If any of the talkgroups are digital (mode 'D' in the database), the 15X won't handle them. No scanner can copy the talkgroups marked 'E' which means encrypted.
If you want to understand how to program your DMA radio, you must first understand what DMA is, what the various special keys are (quick keys, number keys and so forth) and what systems, sites and groups are. I would highly advise you to download the Easier to Read manual for the 15X (or buy the one from Scanner Master) and start reading before you proceed. You can find links at the bottom of the following (all links are in blue)