load dropdownlist in masterpage

Question

hi every body i have popup window un master page which open in button click i want to load dropdownlist in that window but it doesnt load in pageload or in buttonlink click i test the window using button in it it works fine my code is 

if (!IsPostBack)

{

DDlSchool.Attributes["style"] = "background-color:#63B79C;height: 52px;border - radius: 0px;width:175px;";

DDlSchool.Items.Insert(0, new ListItem("-- hello", "0"));

Binddatadropdown(); 

}

 

 or 

 

public void LBcallus_Click(object sender, EventArgs e)

{

DDlSchool.Attributes["style"] = "background-color:#63B79C;height: 52px;border - radius: 0px;width:175px;";

DDlSchool.Items.Insert(0, new ListItem("-- hello", "0"));

Binddatadropdown();

}

 

but it doesnt work where is the problem ??