C2 Week 2 Programming Assignment Error

There is a topic about that on the DLS FAQ Thread.

But note that a first step would be to show us what you see under “Show grader output” on the “My Submissions” page. It doesn’t always help, but sometimes there will be some useful clue about the nature of the error.

Also note that just as a general matter, passing the test cases in the notebook is just the first step and does not guarantee that you’ll pass the grader.