DropDownList Control problem!!

Question

hello Friends.
 
i had created cascading dropdownlist control for same as country/state/city
 
 on page load event m retrieving values of those dropdownlist control..by select query
 
like...
 
ddlcountry.Text=dr[0].ToString();
ddlstate.Text=dr[1].ToString();
ddlcity.Text=dr[2].ToString();
 
on page load event i had filled country dropdownlist control....then on selectedindexchanged event of country dropdownlist control i had filled state dropdownlist control...and on selectedindexchanged event of state dropdownlist control the city dropdownlist control had filled..
 
problem is country dropdownlist control showing its value bt state & city did not...
 
tell me whr m doing wrong?!!