Rectangle with rounded corners and gradient fill - actionscript-3

Question

I'm trying to make a rectangle with rounded corners and a gradient. I have this code:
import flash.geom.*;
var rect:Shape = new Shape();
rect.graphics.lineStyle(5, 0x00ff00, 0); //(thickness, color, alpha)
var fillType:String = "linear";
var colors:Array = [0x000000, 0xFFFF00,0xFFFFFF];
var alphas:Array=[1,1,1];
var ratios:Array=[0,127,255];
var matrix:Matrix = new Matrix();
matrix.createGradientBox(20, 20, 0, 0, 0);
rect.beginGradientFill(fillType, colors, alphas, ratios, matrix) : Void;
rect.graphics.drawRoundRect(720,450, 213.4, 29.1, 12, 12);
rect.graphics.endFill();
addChild(rect);
I'm getting an error from this line :
rect.beginGradientFill(fillType, colors, alphas, ratios, matrix) : Void;
1078: Label must be simple identifier.
I'm a novice and everything I look up seems to have a bunch of terminology I don't quite understand, so please keep it simple.
I want the yellow (FFFF00) to actually be a color picked from the stage so if that can be thrown in there easily without complicating the answer to the above question, feel free.

Answer 1

In your code you have two errors in the same line :
rect.beginGradientFill(fillType, colors, alphas, ratios, matrix) : Void;
We use void ( with lower v, it's not Void ) to indicate the type of a function which will return nothing when we are defining it, not when calling that function.
Then beginGradientFill() is a function of the Graphics class so it should be used with rect.graphics :
rect.graphics.beginGradientFill(fillType, colors, alphas, ratios, matrix);
Then your code can be like this (it's an example) :
var fillType:String = "linear";
var colors:Array = [0x000000, 0xFFFF00, 0xFF0000];
var alphas:Array=[1, 1, 1];
var ratios:Array=[0, 127, 255];
var matrix:Matrix = new Matrix();
matrix.createGradientBox(200, 10, 0, 0, 0);
var rect:Shape = new Shape();
rect.graphics.lineStyle(5, 0x00ff00, 0);
rect.graphics.beginGradientFill(fillType, colors, alphas, ratios, matrix)
rect.graphics.drawRoundRect(0, 0, 200, 200, 12, 12);
rect.graphics.endFill();
addChild(rect);
For more about gradient, take a look on Graphics.beginGradientFill(), and on creating gradient lines and fills ...
Hope that can help.

Answer 2

preface: didn't see the comment from before, but that's the correct solution.
The breakpoint is here:
rect.beginGradientFill(fillType, colors, alphas, ratios, matrix) : Void;
The function call should not have the " : Void" identifier. That's used when the function is originally written.
try this:
rect.beginGradientFill(fillType, colors, alphas, ratios, matrix);