XPath does not pass brower compatibility checks in InfoPath 2007

Question

Why do the targetField attributes below fail the browser compatibility checker in InfoPath 2007. Is there another way to write the statement so that it will work on Browser Enabled forms?

<xsf:ruleSets>
     <xsf:ruleSet name="ruleSet_1">
          <xsf:rule caption="Rule 1" isEnabled="yes">
               <xsf:assignmentAction targetField="my:group1/my:group2[1]/my:field3" expression="my:field1"></xsf:assignmentAction>
          </xsf:rule>
          <xsf:rule caption="Rule 2" isEnabled="yes">
               <xsf:assignmentAction targetField="my:group1/my:group2[2]/my:field3" expression="my:field2"></xsf:assignmentAction>
          </xsf:rule>
     </xsf:ruleSet>
</xsf:ruleSets>

Answer 1

Is the "my:" prefix defined somewhere in surrounding XML you have not shown us? If not, then that might be a reason. The XML you've shown us has no definition for "my:".