Hello, @saminu ! Welcome to the community!
Please, could you share your code in DM with me? Do not share here, It’s prohibited. But this error is probably because the calculation of dj_db is wrong.
Hello @saminu. Even tough i’m not a student from Machine Learning Specialization but a student from Deep Learning Specialization, but like Mentor Lukas said, Please share it through the private chat of Mentor Lukas. You could do that by tapping the profile and click the button message, and feel free to share the code. Don’t put the code here because it breaks your Coursera Honor code.