Transferring a route to Oregon 750t

No geocaches loaded or created on either my Mac or the device and the Oregon was bought new.  Talkytoaster look n feel map installed to both Basecamp & device and then all it's been used for so far is to load other people's routes in GPX format which have worked fine.  This weekend attempted to create a cycle route in Basecamp which worked ok and the new list created fine but get that message when I try to transfer the route to my Oregon. 

Only thing I can think of, and a very long shot, is that Martin who runs talkytoaster is a keen geocacher, wonder if somehow he has screwed up his map?

Might contact him after I hear from Garmin Customer Support in case they have any ideas.  Thanks anyway.

Solved my issue with help from Martin from Talkytoaster and thought it might be helpful to others if I posted here what caused the problem and 2 ways it can be solved.    Martin advised that the message I was getting happens when there are too many waypoints in a route.  I had been creating a point at every turn on the route I was creating.  He advised that when he is creating a road cycling route he uses tracks instead of routes however I got a route to work by starting a new, empty route and dragging and dropping the individual point to point "routes" into a new route where Basecamp automatically combines them into one continuous route.  I now have turn by turn navigation on the cycle route created.  If, as Martin does, you use tracks you will be able to see on the map where you are but you won't have turn by turn navigation.

I find that difficult to believe as in the past I've created routes with hundreds of points, and although BaseCamp can stall if the route is too long and/or complex why on earth would that throw up an error about geocaches?

Glad you got it working though