Change Selected Item Of DropdownList On Button Click?

I have to hidden buttons on my page that I can trigger using JavaScript (__dopostback...). I also have a list of object on my page and a dropdownlist giving the user the possibility to sort those objects on the page. My code checks the current value of the dropdownlist on Databind of the list and applies the chosen sort method to the list. The first button is triggered when the user has selected another sort method from the list.

The second button is triggered when the user adds a new item to the list. Sortmethod "sort2" should be set automatically in the dropdownlist if this happens. So when the second button has been clicked, I need to set the selected item of the dropdownlist dynamically so I can check the value of the selected value later in the DataBind method of the dropdownlist and know what sort method should be applied.

I don't succeed in changing the selected value dynamically. I'm using to controls: First is the objects.vb and the second is the ObjectContainer.vb. Objects.vb contains the two buttons, the dropdownlist and an instance of the objectcontainer. The objectcontainer contains the list with objects that needs to be sorted based on the value selected in the objects control.

Objects.vb:
Private sortMethod As DropdownList
Private container as ObjectContainer
Protected Overrides Sub OnInit(ByVal e As System.EventArgs)
MyBase.OnInit(e)
EnsureChildControls()
End Sub
[Code] .....