hello friends i am having three drop downs and button in my web page naming 1st 2nd and 3rd in which the value of 2nd depends on 1st and value of 3rd depends on 2dn its done using ajax

now when i click on the button it calls one function of ajax which takes value from database and then select value at 1st dropdown and then fire on change event using fireEvent() function which is used to set values in 2nd dropdown and then the function called at button now select value at 2nd dropdown and then fire on change event using fireEvent() function which is used to set values in 3rd dropdown

The main problem is that when i click on button it set value in 1st dropdown but 2nd and 3rd dropdown shows blank values