Mesh index warning at extrusion

[Tim1234]

Hello,

I'm trying to generate a rail track like in your example 25. I copied the generator from the example and fed it with my own spline.
Sadly, the wires and railtracks are not extruded. In the generator I get a warning: "Mesh of index X skipped because vertex count Y > 65534," where X and Y have different values. What does this mean? And why do the wires and the railtracks not extruded? How can I fix this?
It does export something, but it's definitely not right:
https://imgur.com/QWJSrGq

Thanks in advance!