Error in Selectedvalue

Question

hi friends,

I have a dropdownlist2 in a gridview whose datasource and select control parameter is based on the selected value of dropdownlist1 in the same gridview. Everything works great for insert, but when I edit the row in the gridview and change the selected value in dropdownlist1, I get an error of "'dropdownlist2' has a SelectedValue which is invalid because it does not exist in the list of items.