Excercise 4.1 does not accept the call

ERROR: service [/execute_trajectory] responded with an error:
this the error what the shell give so i did not what to do

Can you paste the actual ERROR message?

this happen when i launch the file lanch

those two error is happened whenn i launch it and call

It looks like it can’t find the service package. Check with ‘roscd’ if you can find that specific package and that all spelling is correct.

thank you i will check it