Re: summing attributes problem

  <total><xsl:value-of
select="sum(current-group()[self::po/@cases])"/></total>

<total>
  <xsl:value-of
        select="sum(current-group()[self::po]/@cases)"/>
</total>

--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play

Hi ya'll,
I have a source file as such:
<alldata>
<load>
<start>04/01/06 06:00</start>
<stop>04/01/06 07:30</stop>
<loadnum>300382</loadnum>
</load>
<po num="9865900" cases="206" />
<po num="9872940" cases="5" />
<po num="9877320" cases="290" />
<po num="9880590" cases="450" />
<po num="9880600" cases="418" />
<po num="9886650" cases="282" />
<load>
<start>04/01/06 06:00</start>
<stop>04/01/06 07:30</stop>
<loadnum>300166</loadnum>
</load>
<po num="9873530" cases="630" />
<po num="9880740" cases="1008" />
...
</alldata>
I want to group the po elements with their previous sibling load and sum the
@cases to get:

<load>
   <loadnum>300382</loadnum>
   <start>04/01/06 06:00</start>
   <stop>04/01/06 07:30</stop>
   <po num="9865900" cases="206" />
   <po num="9872940" cases="5" />
   <po num="9877320" cases="290" />
   <po num="9880590" cases="450" />
   <po num="9880600" cases="418" />
   <po num="9886650" cases="282" />
   <total>1651</total>
</load>
<load>
   <loadnum>300166</loadnum>
   <start>04/01/06 06:00</start>
   <stop>04/01/06 07:30</stop>
   <po num="9873530" cases="630" />
   <po num="9880740" cases="1008" />
   <total>1638</total>
</load>

But when I use the following stylesheet, the @cases don't sum and I get the
following error using Saxon8.7
FORG0001: Can not convert string "" to a double...
If I replace "sum" with "count" then it works.

<xsl:output method="xml"/>
<xsl:template match="/cases">
<alldata>
  <xsl:for-each-group select="*" group-starting-with="load">
  <load>
  <xsl:copy-of select="loadnum"/>
  <xsl:copy-of select="start"/>
  <xsl:copy-of select="stop"/>

  <xsl:copy-of select="current-group()[self::po]"/>
  <total><xsl:value-of
select="sum(current-group()[self::po/@cases])"/></total>
  </load>
  </xsl:for-each-group>
</alldata>
</xsl:template>
</xsl:stylesheet>

Obviously I am using xslt2.0.  Can someone explain what I am doing wrong?
TIA

--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play