Have a look, whether there is at least one activity in the route's folder and whether Train Store hasn't removed route's .trk file. If the .trk file is not in place, run unstore everything in Train Store and if it is still not there, reinstall the last update. If .trk file is in the route's folder you have to add at least one activity. If you don't want to install the whole Activity-pack (and download all the required vehicles), you can create an "enabler" activity:
Run train store and choose service mode. Run activity editor and choose to create activity. Then create the player's service choosing one consist and one path (you can also create new ones). Save the activity, don't forget to leave briefing and description EMPTY, though editor will protest while saving. Now you can launch the sim from Train Store as usual. This hint is not usable only with BP, it can also be used with any other route.
