Listbox not scrolling up automatically to show selected item

I have two listboxes, countries and states. When I select a country, first state 开发者_如何学Gothat belongs to the country should be selected in the states listbox. I get the selected countryid and then set the first state that belongs to the country as selected. This works fine in IE8, but in chrome I have a problem. when I first select a country, states listbox scrolls down to select the state. Second time, if I select a country for which the state list needs to scroll up to show the state, it doesn't happen. When i scroll up i see that the item is selected as expected. It's only that the item is not shown in the visible portion of the list. Any suggestion?