You need to have an entry in DSDPlus.Networks, an entry in DSDPlus.Sites, and the entries in DSDPlus.frequencies
DSDPlus.Networks
NEXEDGE48,219,"FleetNet Carolinas"
DSDPlus.Sites
NEXEDGE48,219,4,"site name"
NEXEDGE48,219,9,"site name"
NEXEDGE48,219,23,"site name"
NEXEDGE48,219,24,"site name"
NEXEDGE48,219,25,"site name"
NEXEDGE48,219,28,"site name"
NEXEDGE48,219,29,"site name"
NEXEDGE48,219,30,"site name"
Those are examples. And I can' tremember if the L (L219) is required, or if just the 219. Been a long time now since I've had the opportunity to run DSDPlus on an NEXEDGE48 site.
m