Can't cast event.target

programming flash
1

I’m writing a gallery and I have writen custom Tumbnail class that extends Sprite. Each tumbnail has an ID property so I can determine which one is clicked.

I’ve added event listeners to all of them and in handler function tried:

var target:Tumbnail = Tumbnail(event.targer);

so I can get:

target.ID

but I get this error:

TypeError: Error #1034: Type Coercion failed: cannot convert flash.display::Sprite@33ce241 to Tumbnail.
	at TumbContainer/::onClick()

Anyone know what am I doing wrong?