Page Load of User Control Not firing inside another User control

Question

Hi,

            In my application, I have one user control say UC 1 inside that I have another User Control say UC2. In UC2 there are few DropdownList which I fill in !Ispostback section. Now when I run my application, This !Ispostback section not fire hence dropdownlist wont get filled. I want to fill all dropdown list on load. While debugging control always goes in else part and DropDown List won't get filled.

 Code:
                Page_Load of User Control 2 

        if (!Page.IsPostBack)

        {
              // This part never get called. Why??????
              FillDropDownList();
        }
        else
        {
             //Do something...
        }

         Any help appreciated, Thanks.

Regards,
 
 Vikram