Chapter 2.1 cant locate node

I get this Error:

ERROR: cannot launch node of type [my_cartpole_training/]: can’t locate node [] inpackage [my_cartpole_training]

What can i do?

i solved it thank you

Just to close this question, the typical error when you receive that error message is when you forgot to provide execution permissions to the
Remember that in order to provide such permissions you need to issue the command:
$ chmod +x