Can I use Axes from Attribute Context Node?

I have the following XML fragment

<browseList>
   <MxColumn>SUBCODE</MxCOlumn>
   <MxColumn>SUBDESC</MxColumn>
</browseList>
...............
...............
<bookhouse>
  <SUBJECT>
    <row SUBCODE="ANM" SUBDESC="Animal Science" CREATEDATE="1999-10-10"
CREATEBY"BABY" />
    <row SUBCODE="COM" SUBDESC="Computer Science"
CREATEDATE="1998-12-10" CREATEBY"XYZ" />
    <row SUBCODE="BIO" SUBDESC="Biology" CREATEDATE="1999-01-05"
CREATEBY"ABC" />
    <row SUBCODE="GEO" SUBDESC="Geography" CREATEDATE="1999-08-13"
CREATEBY"BABY" />
  </SUBJECT>
</bookhouse>

What I am trying to do
======================

I want to select

  bookhouse/SUBJECT/row/@SUBCODE and
  bookhouse/SUBJECT/row/@SUBDESC

because these occur under
  /bookhouse/MxColumn

Code I have tried
=================

<xsl:for-each select="/bookhouse/SUBJECT/row">
 <xsl:for-each select="@*">
   <xsl:variable name="columnName"
select="ancestor::browseList/MxColumn/." />
   <!-- error on the above line ClassCast cannot cast to TXAttribute -->

   <xsl:if test='name()=$columnName'>
      <xsl:value-of select=current() />
   </xsl:if>
 </xsl:for-each>
</xsl:for-each>


Am I not allowed to use ancestor from within Attribute Context Node? If
not what will be the solution for the above?

==--==--==--==--==--==--==--==--==--==--==--==--==--==
S.Ramaswamy
Matrix Infotech Syndicate
D-7, Poorti, Vikaspuri, New Delhi, 110018, India
PHONE:    +91-11-5610050,   FAX: +91-11-5535103
WEB         http://MatrixInfotech.HyperMart.Net
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