[xsl] Using xsl:sort to sort negative values

["Sola Awe" <sodana@xxxxxxxxxxx>]

Hi,
  Can anyone tell why the code below will not work?

<xsl:sort select="data" data-type="number"/>

I am trying to sort numeric data that contains negative values but the order 
seems to be wrong

<xml>
<data>22</data>
<data>2</data>
<data>-5</data>
<data>42</data>
<data>0</data>
<data>-1</data>
<data>0</data>
</xml>


This is the output

0
-1
0
-5
2
22
42

I want
-5
-1
0
0
2
22
42