I am producing maps using Mkgmap and Openstreetmap data. the maps I am happy with, lovelly detail the lot.

I am using a Garmin Hcx Legend GPS.

but I have a problem when I ask the gps to route to a point, it produces the route no problems. but the route disappears on the GPS screen, I can see it appears, but then the roads are being places on top of the route. Any suggestions as to what I have wrong ?