Php Ajax autocompletion to be fixed

Hello guys I have a bug on an autocompletion form. Entering a post code should select a range of cities recorded in my database It works fine on a twin site, not on the other. I need someone who can help in finding the issue. Script is installed ! Nothing to code, just a fix to be found and to let it work. This is a one hour job... I won't pay more than One hour so bid only if you are sure you can deal with that in this laps of time. Confirm that you have understood my request by adding "OK FOR A 1 HOUR JOB FOR THIS BID" at the end of your price offer. Thanks