DLS Course1 Week3

That probably means there is something structural wrong with your notebook. E.g. that you’ve broken some other part of the code that the grader depends on. Please show us the output you get from the “Show grader output” option on the “My Submissions” tab.

Or if you want to try a fix, the first thing would be to follow the “Get a Clean Copy” procedure on the FAQ Thread and then very carefully copy just your code from the “YOUR CODE HERE” sections into the clean notebook and see if that helps or not.