Hi All,
I have one update panel having combo box and button inside this.
When i refresh page and change default selected item in the combo box and click the button,
grid generates but without showing loading panel image, sometime the loading image gets display when i click more than one time the button after combo box item selection.
I investigated further and found that the issue was with IE 6, when user select item from combo box, it takes some time add again in combo box on server side, even it will show on client side.