Radcombobox Selected index changed problem

[Velkumar]

Hi,

          I have two combo box  , one for country another one for state.  Depends upon the selection in Country combo i will load the states in states Combobox.

                             I have selected index changed server side function for both the combo box.  I have set the Autopostback property for the both the combo box as false.

                              In the client side selected index chnaged function I have used the __doPostBack   function with corresponding combobox unique id  as EventTarget.

When i select any country both country and state server side selected Index changed function will be called. 
   
            My problem is when I select the state in the state combo box again both functions will be called. Here I can't understand why the country selected index changed function is called.

I have placed both the combobox in asp updatepanel. I have set the trigger of the country update panel  is the country combobox and the trigger for the state update panel is  also country combo box.

**** I want to know how these events will be handled and how these functions called depends on this events.

Please give the solution for this problem.


Thanks
Velkumar.