Change Control properties from a GridView's Command event

Hello everybody,

 I've a problem updating a Control's property when clicking any kind of Control inside a GridView's row.

In other words, I have a ListView and a GridView populated from an ObjectAdataSource. At the beggining I added a template column with a CheckBox with AutoPostPack enabled.

Each time a CheckBox is clicked, I need to check it's Checked state and if it's checked, I add the corresponding row to the ListBox control. On the other hand, if the CheckBox is not checked, I need to remove the corresponding row from the ListBox control.

I was able to get everything to work, but for some reason, every time I check a row in my GridView and add it's description as a new ListItem in my ListBox, I can't see the new ListItem in the page. When debuging, everything works fine, but at some time the ListBox is cleared. I thought it had something to do with me using a CheckBox with OnClick event instead of ...