Reason could be any of the below for grading failing according to the details shared by you
- any code error especially related like using global variable instead of local variable or vice versa.
- Removing any of the codes or instructions outside of markers ###START AND END CODE HERE###
- if you have added too many #print options
- if you have added or deleted any other cells other than grade cell.
- if you have renamed your assignment file.
- CHECK if you have left any None between the codes.
to resolve this issue in case you are confident of your codes, then get a fresh copy and re-do assignment.
To get a fresh copy follow below link, refer 1a
But make sure this time you only write codes between markers ###START AND END CODE HERE###
Regards
Dp