Dijkgraaf - 11:47 pm on Nov 4, 2012 (gmt 0)
The prefix needs to be identified in the root of your XSLT.
See [w3schools.com...] where it has this in the root
and the following as the if expression.
<xsl:if test="price > 10">
Notice how the xsl: is defined as pointing to XSL Transform namespace.