Channels not heard in scan mode

I have the bcd436hp with only 5 channels loaded onto in from the sentinel software. It only scans 2 nearby sites on the Ohio MARCS system. In scan mode it receives audio from 2 channels that are "dispatch" channels (both from different sites), however nothing comes in on the 3 channels listed as "tactical" channels. These are not encrypted channels. If you manually stop the scan on one of the tac channels, the radio traffic will come in. Any idea how to get them to come in while it is scanning?