Web Forms :: Checkbox Can't Be Added Into Panel?

I am using asp.net panel control in which I am adding two controls(a literal that contains some text and a checkbox) in code behind.

The code is something like this....

CheckBox checkBox=new CheckBox();
checkBox.ID = "chk_id";
checkBox.Text = "chk_text";
pnl_cityNames.Controls.Add(checkBox); //add check box
pnl_cityNames.Controls.Add(new LiteralControl("Some Text<br>")); //add some text

and to retrieve I am using this code.....

foreach (Control var in pnl_cityNames.Controls)
{
if (var is CheckBox)
{
int abc = 0;
}
}

When I run this code in the debug mood, It shows two added controls

1.)Text="Islamabad" checked=false

2.)System.Web.UI.LiteralControl

This is what the problem I am facing, it should add checkbox in the same manner as LiteralControl. So I am unable to get any condition to be true when I check the var for CheckBox in the foreach loop.