[mkgmap-dev] Routes being overwritten

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 ?