PHP - works on local server but not on remote?

I am making a site which uses an XML database which is parsed by PHP and the data passed into an PHP array (learnt this from the XML Parsing using PHP { Intermediate } tutorial). From there the data is outputted onto a webpage as neccesary. It works fine on my PC’s local server which is PHP v5.0.5. However once the site is uploaded to my client’s server (PHP v4.3.10), when the values taken from the XML database exceed approx. 1000 chars, the PHP fails to display any more characters than that, and other PHP functions on the page fail to display correctly too. Any suggestions on what I can do?!