Problem creating routes

Hi all, im creating a new route for a group trip, im finding when I try to enter a nav point it isn't routing to the point I want via a known track or road, it goes back and I get a grey line pointing directly through the bush to the the point I want, I can't seem to get this thing to go straight along a track. I've tried to set shorter way points but that's really time consuming and I'd need dozens of them to work around this.

Ive attached a screen shot of what im getting once I set the waypoint