Please indicate full data!! We cannot not infer what what is the problem with so little data.
Which course, provide full screen capture, which unit, which browser, previous commands launched, I don’t know… everything that may be useful for answering your question.
We cannot help you if you do not take the time to write a proper question.
About your problem, here a quick answer just to see if it heps:
Do a source of your catkin workspace and see if that works. For that, type the following command: source /home/user/catkin_ws/devel/setup.bash
Since now is weekend, do not expect fast response to your answers (our Forum customer support times are from Monday to Friday).