How do I use an xdoxslt variable inside xsl code, in BI Publisher?

Question

I am trying to create a loop that increments a variable, then use that variable inside of some xsl code. Here is the code I am using to increment the counter:

<?xdoxslt:set_variable($_XDOCTX, ‘counter’, 0)?>

<?for-each-group:$g2;./STATUS?>
<?sort:current-group()/STATUS;'ascending';data-type='text'?>
<?xdoxslt:set_variable($_XDOCTX, ‘counter’, xdoxslt:get_variable($_XDOCTX, ‘counter’) 
   + count(xdoxslt:distinct_values(current-group()/ACTION)))?>
<?end for-each-group?>

The following code will output the number that I need:

<xsl:value-of select="xdoxslt:get_variable($_XDOCTX, ‘counter’)"/>

So I know the loop is working and the variable is has the correct number. However, I need to use the variable in the following code:

<xsl:attribute name="number-rows-spanned"  xdofo:ctx="block">
<xsl:value-of select="xdoxslt:get_variable($_XDOCTX, ‘counter’)"/>
</xsl:attribute>

When I use it this code I get the following error:

java.lang.NumberFormatException: For input string: ""

I have also tried:

<xsl:variable name="rowcount" select="xdoxslt:get_variable($_XDOCTX, ‘counter’)"/>
<xsl:attribute name="number-rows-spanned"  xdofo:ctx="block">
<xsl:value-of select="$rowcount"/>
</xsl:attribute>

This results in the same error. Is there any workaround that will allow me to use a variable in this way or should I just find an alternate solution?

This is the report I am trying to create:

Group by Column1

    Group by Column2

        Column3    | Column4    | column5   | Column6
        Group Left | Group Left | Group Left | Number

    End Group by Column2

   Totals

        Column3    | Column4    | column5   | Column6
        Group Left | Group Left | Group Left | sum()

End Group by column1

The problem is that in the "Totals" table, Column6 values are being split when there is more than 1 Column2 in the grouping.

Solution

I found a workaround, I would prefer a more elegant solution but at least it works. What I did was made the last column basically a "ghost" column (no field and no borders). Then I inserted a table with two columns into column5. The tags where placed before and after the table. In the table I put the value for column5, and the sum I needed in column6. It's not perfect, there are some small formatting issues. I would prefer a better solution, if anyone has any suggestions.