Issue with old website not connecting to SQL

I have being to debug this connection http://mymobilehairdresser.com.au/mobile-hairdresser-areas-covered.php?postcode=5169&submit=Check+Now

it is from an old website, but for the life of me I can’t see why it won’t work, when it should do.
Could I ask for a set of fresh eyes to see if anyone can see the issue.

Thanks