Compile error 1046

Hello All, I have been going crazy for hours. I keep getting this compile error:
1046 Type was not found or was not a compile-time constant: ComponentEvent.
I think Flash is telling me i have have not imported the proper class. However, when i try and fix the problem the error still keeps popping up:puzzle:.
This is my code: Im building a combobox on stage do i need a componentEvent? If you can identify were i am going wrong i appreciate it if you could give me some advice. T
hanks Ricky

aBb.dataProvider = new DataProvider(items);
aBb.addEventListener(ComponentEvent.ENTER, onAddItem);

function onAddItem(event:ComponentEvent):void { THIS ERROR LINE <<<<<<<<<
var newRow:int = 0;
if (event.target.text == “Add”) {
newRow = event.target.length + 1;
event.target.addItemAt({label:"" + newRow, data:“Data” + newRow},
event.target.length);
}
}