Just got my submission rejected

My submission got rejected, received this email, can someone explain whats the issue?
I made the 404 page and submitted it.

It’s impossible to tell from a thumbnail - presumably, you submitted a working version or is it just a PSD design?

Well it was a working website made using HTML, CSS

It’s a tough category to be approved in and find premium value. Try sharing your demo link here which would make it easier to give feedback