Column Calculations in XSLT

Hi to all,

I was doing straight summation on the column level using the
sum(Range/purchase) function and was doing great. But when I tried more
complex calculations like

sum(Range/purchase * Range/Quantity) I couldn't generate the output
file.

Instead I got the following:

"Error in XSL processing Can not convert #UNKNOWN to a NodeList!"

Any idea on how to do these calculations.

Thanks


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