p:commandButton not working inside a p:dataGrid

If you are having a trouble with p:commandButton that is not working inside a p:dataGrid, make sure you have a p:column as a child for the p:panelGrid as follows:

<p:panelGrid .. >

<p:column>
...
<p:commandButton ... />
...
</p:column>
</p:panelGrid>

if you forget the p:column, the button event is not executed.