Problem with comboboxes

Question

Here's the situation: I have a form with different panels. The panels become visible/unvisible depending which button the users clicks. One each panel there are a few comboboxes. (in usercontrols) I want them all to be empty. For this, i set selectedvalue to -1. The first time i go to a panel (so the first time it gets visible) it works fine. But when i go to another panel, and return to the previous one, all of the comboboxes have the first item selected! anyone with similuar problems and solution? Selectedindex, selecteditem give the same problem. mbr