It might be that the form is using the $fieldname which corresponds to the input box field name. In later versions of PHP this feature (called register_globals()) is turned off.
If you have access to the PHP.ini file, you can change the register_globals =1 to turn it on.
If you do not have ability to change this in the .ini files, check to see if you can alter this in the runtime (search the manual on making runtime changes...sorry at work and unable to spare much more time)
The third option is to open every file and change the name of the variable of the form element to use $_GET['elementName'] or $_POST['elementName']. Ie
you have a textbox for first name
<input type=text name=fname> and on the corresponding PHP page you have a variable called $fname which automatically takes the value of the form element fname.
This $fname needs to be changed to $_POST['fname'] if the form uses the POST method or $_GET['fname'] when the form uses the GET method of passing data.
