Double dashed lines like you show occur when you have any spline, track, road, hedge, etc, that is missing. You will need to check in CM to see what dependencies are missing from the route and download them from the DLS. If you are really unlucky they might show up as unknown and these will need a bit more detective work, try a google search, that usually finds most missing dependencies. If you are still unable to find them post them back here and I expect someone will be able to point you in the right direction.
