Quick question (hopefully)....

I have an XSL document that is used to display data from a table. The issue that I am having is when it comes to the field values in said table. I want to be able to display the hyperlinks, if they exist, or "No Data" if a hyperlink does not exist in a particular field. The issue lies down in the "xsl:choose" section....there is a nested "xsl:if" statement inside the first "xsl:when" statement. I have chopped down the code to save space and since all other "xsl:when" statements that are between the first and last statement are just variations of the first (different fields, but same output type).

Any ideas?

Here is my code for reference:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:fo="http://www.w3.org/1999/XSL/Format">
<xsl:template match="/">

<base target="main">
<title>Photo Archive</title>


<div position="absolute" width="300" height="400">

<table cellpadding="1" cellspacing="0" width="300" height="75" border="3" style='border-collapse:collapse;position:absolute;top:0pt;'>

<th width="115" valign="center" bgcolor="#000000">
<img valign="center" align="center" width="75" height="75" border="0" src="T:\FS\NFS\ArapahoRoosevelt\Program\2400TimberMgmt\CLRD\2470Silviculture\PhotoArchive\ARNF_Photo_Archive\ARNF_Photo_Archive_REF\FSshield.jpg" alt="FSshield"/>

 <td width="185" height="37.5" bgcolor="#3D6600">
<p text-align="center" style="font:20pt Verdana, sans-serif; color:#ffffff;">
<span style="font-weight:bold">US Forest Service</span></p>

 <td width="300" colspan="2" height="37.5" bgcolor="#000000">
<p text-align="center" style="font:16pt Verdana, sans-serif; color:#ffffff;">
<span style="font-weight:bold">ARNF Timber Archive</span></p>

<xsl:variable name="nameCol" select="FieldsDoc/Fields/Field/FieldName"/> 

<xsl:variable name="index" select="1"/>
<xsl:for-each select="FieldsDoc/Fields/Field">

<xsl:if test="(position() +1) mod 2">
<xsl:attribute name="bgcolor">#6e903b</xsl:attribute>
<xsl:if test="string-length($nameCol) != 0">

              <xsl:value-of select="FieldName"/>

 <xsl:when test="FieldName[starts-with(., '2005 North')]">
 <xsl:variable name="imageURL" select="FieldValue"/>
	<xsl:if test="FieldValue !=null">
	<xsl:variable name="null"/>
	<a href="{$null}">No Data</a>
	<a href="{$imageURL}" target="_blank">North Photo</a>
 <xsl:when test="FieldValue[starts-with(., '\\')]">
 	<a target="_blank">
	<xsl:attribute name="href">
	<xsl:value-of select="FieldValue"/>
	</xsl:attribute><xsl:value-of select="FieldValue"/>
            <xsl:value-of select="FieldValue"/>