Dropdownlist_OnSelectedIndexChange Evnet inside the Child Gridview - Not firing

Question

I have some dropdownlsit is placed inside the Gridview ie:

Gridview -> inside this Another Gridview ->> here the Dropdownlist are there

I already set AutoPostback =True and

OnSelectedIndexChangeEvent="Dropdownlist_SelectedindexChangeEvent"

and also i have written eventhandler on Code but its not fire on live ,

but this code works on Localhost , when i upload to my Server

the Dropdownlist_SelectedindexChangeEvent Not working why

Any Solution ??