flex4 1195 error when calling a function (not get or set)

I have a class called S3Uploader which extends Sprite, which has a private function init, which looks sometihng like this:

private function init(signatureUrl:String,  
                              prefixPath:String, 
                              fileSizeLimit:Number,
                                queueSizeLimit:Number,
                              fileTypes:String,
                              fileTypeDescs:String,
                              selectMultipleFiles:Boolean,
                                buttonWidth:Number,
                                buttonHeight:Number,
                                buttonUpUrl:String,
                                buttonDownUrl:String,
                                buttonOverUrl:String
                                ):void { 
//do stuff

}

In my flex app, I am trying to display the sprite and call the init function when the app is loaded. my code so far is this:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"
                initialize="init();">
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, valu开发者_如何学Goe objects) here -->
    </fx:Declarations>
    <fx:Script>
        <![CDATA[
            import S3Uploader;

            function init() {   
                var s3upload:S3Uploader = new S3Uploader();
                s3upload.init('/s3_uploads2.xml', '', 524288000, 100, '*.*', 'All Files', true, 100, 30, '/images/upload-button.png', '/images/upload-button.png', '/images/upload-button.png');
                uploader.addChild(s3upload);
            }
        ]]>
    </fx:Script>
    <s:SpriteVisualElement id="uploader" />
</s:Application>

however, on the line where i call s3upload.init, i get a 1195 error saying "1195: Attempted access of inaccessible method init through a reference with static type S3Uploader."

When i looked up this error, it seems like almost everyone getting this was trying to call a function with set or get. However, I am not doing this and i have no idea why i am getting this error. Does anyone know what I am doing wrong?

You should learn the basics of OOP. You cannot call private functions from not within function owner objects. Mark it as public.