How do you select an item in a combo box when you are creating the items dynamically:

Code:
combomenu.menu = new Ext.menu.Menu();

for (i=0;i<comboitem.length;i++)
{
	combomenu.menu.add({
		text: comboitem[i],
		value: comboitem[i]
	});
}
I tried using "checked" and "selected" but neither worked; I also tried to use the following but it just returned an error:

Code:
combomenu.selectByValue(jsonObj.comboitem, false)
Error:
Code:
combomenu.selectByValue is not a function