When you want to display progression in an indicator in a loop (not through the On Timer event), you need to use the redraw command to update the display of the indicator object. For example the following code updates the value of MyIndicator but the progression is not displayed:

Case of
 : (Form event=On Clicked )
 MyIndicator:=0
 For ($i;1;10000)
  MyIndicator:=$i
 End for
End case

With this code, the indicator is updated at the end of the loop. If you want to display the progression, you need modify it as follows:

Case of
 : (Form event=On Clicked )
 MyIndicator:=0
 For ($i;1;10000)
  REDRAW(MyIndicator)
  MyIndicator:=$i
 End for
End case