Submitting not working

Hello sir
From what my senior replied to me there seems 2 plausible reasons for it
1)Are you using any undeclared parameters or any global variables?
Can you please send me your notebook so that I can have a closer look…please send your notebook in a private message to me by clicking on my name to not violate the Honor Code of Coursera
2)Are you enrolled in this course for a while then it might be that you are in an old session and in that case can you please follow steps given at

Please do let me know after trying second solution and if that doesn’t work then please send me your notebook on pm as described above

Thank you for your patience and cooperation sir