My Nuvi 1370 does not see my new map

[Schnee]

I've made a new map using GPSMapedit, Mapset tool kit and BaseCamp.
I can open it in BaseCamp and load it into my Nuvi 1370.
The problem is that it seems to ignore it: The map is not listed in Maps - info.
Furthermore, when I display my area and zoom out, when the area coverd by the new map comes in the range, nothing is displayed.
I've downsized the map to a ridiculously small sample but it makes no difference. There must be somthing wrong with the file, but what?
I've attached this sample.
Can anyone tell me what's wrong?