Transferring GPX files to Nuvi 2597

I'm getting really frustrated with Basecamp - can anybody please offer a suggestion?

I have a Nuvi 2597 which has the North American map in the main memory and Western Europe on the Micro SD.

I'm planning a driving trip around the Alps and have been sent a GPX file of the route by the tour company - it will take 5 days and appears as 5 legs in different colours on the Basecamp map.

I created a list in Basecamp and imported the file and I can see the full details of the route, turns etc. All good so far.. So then I select transfer to device and Basecamp offers the choice of the Nuvi or the Micro SD. I select one or the other and I get a very quick "Saving" message, and then a Close message - the "Saving" is probably only a second or so.

When I fire up the Nuvi and go to Apps:Trip Planner, at most I get the first day of the route - but not the remaining 4 days. So I've split the main GPX file into 5 segments and tried to transfer each one separately - then I get nothing.

I must be doing something wrong - anybody have any idea on what it is? Also, as I can see the contents of the main Nuvi Drive and the Micro SD in Finder, is there an alternative just to copy the files directly into those directories, without using the Basecamp transfer. If so, where should the gpx files go?

Thanks

Wallis