Sorry, you'll have to show more of your input and output and explain what the extension functions do. It's also not clear why you would want to use disable-output-escaping.
In XSLT 1.0 if xsl:value-of is given a node-set as input, it displays the string value of the first node in the node-set. That might be relevant to your problem.
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference