SKIP ROW based on an attribute in one sheet of a multi sheet excel template

Summary

I have a summary and detail excel template. I need to suppress rows which have a value of zero on one particular attribute of the row.

Content

I have inserted the following in Data Constraints of the XDO_METADATA.

<xsl:if test="number(.//COST_DIFF)!=0"> <xsl:value-of select=".//COST_DIFF"/> </xsl:if>

COST_DIFF is in the Detail sheet and the rows to be suppressed from display are in the Detail sheet only.  However it's not applying this because I think somewhere we should say this condition is for the detail sheet.

Any ideas are much appreciated.

Dilip