Multiple Sort Key Components

Hello,
I'm attempting to sort the content of a variable using multiple sort key
components and my last component (@range_length) doesn't take effect. Given
this input which reflects paragraphs in document order:
B <list_of_group_ranges>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="2"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e70"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e141"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="10"/>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="3"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e70"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e160"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="14"/>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="4"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e70"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e102"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="5"/>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="17"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e174"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e214"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="26"/>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="18"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e174"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e193"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="22"/>
B B B B B B B B B B B B B B B B B B B B B B B  <range comment_id="23"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
start_element="d34e203"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
end_element="d34e209"
B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B 
range_length="25"/>
</list_of_group_ranges>
I want to sort these according to 3 sort components:1. document order2.
@start_element value3. @range_length value
The code I'm using to sort is:
B B B B B B B B B B B B B B B B B B B B B B  <xsl:for-each
select="$list_of_group_ranges/*">B B B B 
B B B B B B B B B B B B B B B B B B B B B B B B B B B  <xsl:sort
select="position()"/>
B B B B B B B B B B B B B B B B B B B B B B B B B B B  <xsl:sort
select="@start_element"/>
B B B B B B B B B B B B B B B B B B B B B B B B B B B  <xsl:sort
data-type="number" order="descending"B 
select="@range_length"></xsl:sort>B B B B B B B B B B B B B B B B B B B B B B
 B B B B 
B B B B B B B B B B B B B B B B B B B B B B B B B B B  <xsl:copy-of
select="."/>
B B B B B B B B B B B B B B B B B B B B B B B  </xsl:for-each>
But the last sort component, @range_length, isn't taking effect as the <range>
elements with the same @start_element don't sort according to @range_length.
What am I missing?
Thanks
Don