PHP Version problem?

I'm running PostNuke CMS on a server that I have control over. I get the following error after submitting a form:

Fatal error: Undefined class name 'parent' in includes/textsanitizer.php on line 142

this is line 142
$text = parent::sanitizeForPreview($text,0,0,0); //do htmlspecialchars

might this have something to do with the php version?

I don't know what version is on the server? How can I find out if it is that?

first, do a <i>phpinfo();</i> on a page to see what version of PHP you are using.

-- Rich

I have php Version 4

Is the code for which you are getting the error something you wrote or was it part of the <i>PostNuke</i> package?

-- Rich

It is part of postnuke. There seem to be a few more errors happening elsewhere too.

Any ideas?