Unintelligible error when using a function FOLLOW ME - this is not a valid path!

[colin]

I found that we have been through this problem before, 4 1/2 years ago.

I can't use Follow Me on very large arcs

I tried deleting everything in your model until there was just a single line arc. Selecting that and trying the follow me tool gave an error about how it didn’t seem to be a valid path. If you select the arc tool and type 200 Enter, to make it be a 200 segment arc, then click on one end of your old arc, then the other end, then raise the new arc up to the height of the old arc (in other words, remake the arc), it then will work with the follow me tool.