if the query returns no result, I want to display a blank panel with no text or value.
try a depends/rejects with a conditional token to replace the panel with an empty html panel. Here is just a random syntax you can pick apart for the xml.
<row>
<panel rejects="$blankpanel$">
<table>
<title>title here</title>
<search>
<query>|makeresults|eval blank=""|fields - blank _time</query>
<earliest>-24h@h</earliest>
<latest>now</latest>
<progress>
<condition match="'job.resultCount'=0">
<set token="blankpanel"></set>
</condition>
</progress>
</search>
<option name="count">10</option>
<option name="drilldown">none</option>
<option name="refresh.display">progressbar</option>
</table>
</panel>
<panel depends="$blankpanel$">
<html>
<b>title here</b>
<br/>
</html>
</panel>
</row>
@cmerriman works great. Thanks