xslt_process

I'm trying to use Sablotron to server-side parse my XML. I've used an RPM of php 4.3.4 on RH9. I'm using also Plesk 6, a virtual hosting environment. After installing this RPM, I run the www.domain.com/phpfile.php?x=file.xml and I get the warning XML parser error 3: no element found in ......... on line 85 My line 85 says: xslt_process($this->processor, 'arg:/_xml', 'arg:/_xsl', NULL, $arguments) so I assume xslt_process is the problem (don't know why, worked in php 4 .3.3). All different XML & XSL files cause the same error. I would really appreciate it if someone could give me some pointers on a workaround for this, I'm desperate!! THANKS!!!!!!!!!!!!!