XSLT - How to select XML Attribute by Attribute?
Just remove the slash after Data and prepend the root:
<xsl:variable name="myVarA" select="/root/DataSet/Data[@Value1='2']/@Value2"/>
There are two problems with your xpath - first you need to remove the child selector from after Data like phihag mentioned. Also you forgot to include root in your xpath. Here is what you want to do:
select="/root/DataSet/Data[@Value1='2']/@Value2"
Try this
xsl:variable name="myVarA" select="//DataSet/Data[@Value1='2']/@Value2" />The '//' will search for DataSet at any depth