Grid component whoa's

[nhhockeyplayer nashua]

Hi Folks,
 
I am operating grid component. it renders nicely onSubmit
 
@SetupRender
public void setupRender() {
 grid.reset();
 if ( grid.getSortModel().getSortConstraints().isEmpty() )
 {
  grid.getSortModel().updateSort("gp");
  grid.getSortModel().updateSort("g");
  grid.getSortModel().updateSort("a");
  grid.getSortModel().updateSort("pts");
  grid.getSortModel().updateSort("ppg");
  grid.getSortModel().updateSort("ppa");
 }  
}

Can anyone explain why this grid disappears when I click a sort column?
 
is this all i need to do to ensure column sorting support?
 
thanks

Best regards 
and thanks... KEN