Routing over road or parking area where there is no trail?

Sorry if this is a simple task but I am really struggling with it. When I am creating a route and come across an area where a trail crosses a road or a parking lot Basecamp simply freaks out and will not route across it. I am sure there is a way to overcome this but I cannot figure it out. As soon as I try to route across an area like this it reverses the route and goes all the way around to the other side rather than straight across. ciq.forums.garmin.com/.../1365449.jpg