The error message is useless as so often. The correct message should be "The calculation does not converge to a solution."
Set t.end to 1.6469 s (instead of the 7 min) and the system solves. If you look at the graph you may guess why it doesn't work for a higher end value.
Ich bedanke mich, Werner!
You are our ambulance!
I have forgot the minus but PTC has forgot to give a correct error message:
(It is a problem of a boat stop)
