Trying to get sounds to play on keystroke in AS3

1

[FONT=Arial][SIZE=2][COLOR=#000000]stage.addEventListener(KeyboardEvent.KEY_DOWN, fl_KeyboardDownHandler_4);

function fl_KeyboardDownHandler_4(event:KeyboardEvent):void
{
if (event.keyCode == "40") bassd.play();
        if (event.keyCode == "37") tlow.play();
  if (event.keyCode == "88") snare.play();
  if (event.keyCode == "38") cym.play();
  if (event.keyCode == "83") thigh.play();
  if (event.keyCode == "68") tmid.play();
  if (event.keyCode == "90") hh.play();[/COLOR][/SIZE][/FONT]

Getting the following error for each line - what am I doing wrong??

[FONT=Arial][SIZE=2][COLOR=#000000]Symbol 'drum', Layer 'actions', Frame 1, Line 9 1176: Comparison between a value with static type uint and a possibly unrelated type String.
[/COLOR][/SIZE][/FONT]