Custom Registration for Custom Databases

i have made custom registration page using custom database,

my script like bellow:

[ 301 lines of code moderated, that’s just way too much. For that many lines of code please use pastebin.com instead. ]

when load the page, it was success. but when i try to register and submit data, it not showing me error / success message, it always redirect me to 404 page.

how to make it running perfect?