setInterval not working in AS2 Class

programming flash
1

Hi I have the following strange problem…

public function showImageAt(num:Number):Void 
{	
	var interval:Number = setInterval(
	  function():Void {
	trace("WORKING"); // works
	test(); // doesnt work
	    clearInterval(interval);
	  },
	  500
	);
}

private function test():Void
{
trace(“test”);
}

so the test function never gets called… anyone could help me on this one?