ActionScript 3.0 :: Property BitmapData.getVector Not Found

I'm trying to use the getVector() method of the BitmapData class to sort through the pixels of a BitmapData object and change all pixels of a certain color transparent. However, whenever I attempt to make a call to the method, Flash Builder (4) spits out an error. Here is an example of a line of code I've moved to the constructor of my main class for simplicity:

ActionScript Code:
var v:Vector.<uint> = new BitmapData(GAMEW, GAMEH, true, 0).getVector(new Rectangle(0,0,40,40));

At runtime, the console spits out "ReferenceError: Error #1069: Property getVector not found on flash.display.BitmapData and there is no default value."

When I try to execute the method in the function I actually want it in, which has a BitmapData object passed as the parameter, I get a different error. Here's the relevant snippet from the function:

ActionScript Code:
private function convertAlpha(bm:BitmapData):BitmapData {
var v:Vector.<uint> = bm.getVector(bm.rect);
...
return bm;
}

This spits out the error "TypeError: Error #1006: getVector is not a function."

I'm clueless as to why it's not recognizing the method, Flash Builder even suggests it to me as a method when I add a dot after a BitmapData object.