VPS2 (Virtual Private Server)

I have not used PHPrunner for a while and recently updated my hosting package from a standard UNIX to a new VPS2 (Virtual Private Server) I have been testing the new beta 241 phprunner 4 but keep getting the same error.
Fatal error: Call to undefined function: xml_parser_create() in /home/dbaseonline/www/dbaseonline.co.uk/tadimar/include/commonfunctions.php on line 633
I have upoloaded phprunner.php to the dbaseonline.co.uk and connerted to the dbase no issues there, I then upload the output file to the tadimar dir but no matter how I do it I still have the same error.
So I am now thinking it must be something to do with the VPS, does anyone here have any knowledge of phprunner working on vps.
The VPS has PHP4 and phpMYAdmin installed on it and they seem to be working fine.
Any help our ideas gratefully accepted,
Let me say phprunner is a great product and I have never had any problens with it until this one.
Thanks

Bobby