node()[not(processing-instruction()] not working

The below XPath expression is supposed to select all children of the
named 'page' element except processing instructions with the name
'php-predoctype'.

<xsl:apply-templates select="page[@name='register']/node()[not(processing-instruction('php-predoctype'))]"/>

Unfotunately it doesn't work. The not() clause doesn't appear to have
any effect as php-predoctype nodes are selected regardless. Can someone
point out what I'm doing wrong?

The following XPath expression does come very close to producing the
expected results but of course it is logically inferior.

<xsl:apply-templates select="page[@name='register']/*|page[@name='register']/processing-instruction('php')"/>

Could this be a bug in the processor (xsltproc form libxslt-1.1.15)?

Mike

-- 
Michael B Allen
PHP Extension for SSO w/ Windows Group Authorization
http://www.ioplex.com/