Anchor tag in XSL

In my XSL there is an anchor tag. When this anchor tag is clicked I want a JAav function to be executed. This is what I am doing in my XSL

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:java_func="com.common.utils.SUtils"
xmlns:java_func_1="com.components.detailedView.FkDetailedView"
extension-element-prefixes="java_func java_func_1" version="2.0">
...
...
...
 <td>
                     <xsl:for-each select="fb_holder/attached_files/file_details">
                           <a href="java_func_1:fileViewer('0900054d8000cf8e')"><xsl:value-of select="file_name"/></a><br/>
                    </xsl:for-each>
 </td>
But upon click it gives an error. Can someone please let me know how to resolve this.