Netscape6.x not recognizing data-type="number" on xsl:

I am sorting a number of responses to a questionnaire by an attribute of my 
Respondent element called Sortno.  I am using the attribute, 
data-type="number" in my xsl:sort statement.

The view I get in my IE6 browser is:

Sortno
1
2
3
4
5
6
7
24
46
which is the correct numerical sort.

The order I get in Netscape6.x is:
1
2
24
3
4
46
5
6
7
which is the text sort.

If I create an html document by executing Dave Clark's XT from the Command 
Line, I get the same results as the IE6 view.  That is, the desired result.

Any ideas?

Jerry Yurow

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list