xsl:for-each , evaluate question

Hi

I am trying to write xsl:for-each loop as follows :

<xsl:for-each  select="report/row[col='some value']">
This works fine.

But my select part has to be dynamic, as the filter condition will change each time. Therefore i tried this :

<xsl:param name="filterCond" />
<xsl:variable name="completeFilterCond" select="concat('/report/row[' , $filterCond, ']' )" />
<xsl:for-each select="$completeFilterCond">

Where the filter condition gets passed as a parameter to the XSL file.

In this case i get the following error :

Can not convert #STRING to a NodeList!

Would appreciate if someone can help me solve this problem.

thanks
Jitender.