Entry event

Hello everyone, 

I have a problem when I try to launch an action after a change of my entry. My entry is define by :

 set listing [list '0' '1' '2' '3' '4'];
 set entry2 [hwt::AddEntry $frame2.entry2 \
 label       'Choose :' \
 labelWidth  $labelWidth  \
 entryWidth  20 \
 listVar fromPopDown noTyping [namespace current]::listing \
 state normal \
 anchor      nw \
 validate    real \
 text        '0' \
 textvariable variablePicked \
 selectionFunc {tk_messageBox -message 'Changed !!!!'}];
 pack $entry2 -side top -anchor nw;	

I was in HW GUI ToolKit some function as selectionFunc but It doesn't work ! May somebody have any ideas ?

Thank you a lot for your help