I have a Doc Type called Blog - In short everything under a content node can create a blog. Along with this is the date for the blog. I'm trying to count the number of blogs for each month using XSLT and have the below but is giving me the incorrect count?

<xsl:key name="MonthNo" match="Blog" use="substring(concat(currentDate, @createDate), 1,7)"/>

<xsl:template match="Blog" mode="month">
<xsl:variable name="DateBlog" select="concat(currentDate, @createDate)"/>
<xsl:variable name="YearBlog" select="substring-before($DateBlog, '-')"/>
<xsl:variable name="MonthBlog" select="substring($DateBlog,6,2)"/>
<xsl:variable name="BlogsInMonth" select="key('MonthNo', substring($DateBlog,1,7))"/>
<li>        
  <xsl:element name="a">
    <xsl:attribute name="href">
      <xsl:value-of select="umbraco.library:NiceUrl(1234)"/>?d=<xsl:value-of select="concat($MonthBlog, '-', $YearBlog)"/>
    </xsl:attribute>
    <xsl:value-of select="concat($monthNames[position()=$MonthBlog], ' (', count($BlogsInMonth),')')"/>
  </xsl:element>
</li>

Can anyone see where ive gone wrong or the mistake made? Struggling with this so any help is appreciated.