Inheritance - how to extend a class

1

I am working on inheritance for the first time

Here is the super class
SetBlank.as


import flash.text.*;
class SetBlank {
    public var _textFieldName:TextField;
    public var _defaultName:String;
    public function SetBlank(textFieldName:TextField, defaultName:String) {
        _textFieldName = textFieldName;
        _defaultName = defaultName;
        if (_textFieldName.text == _defaultName) {
            _textFieldName.text = "";
        }

    }
}

I just want to inherit all the feature from SetBlank to ExtendSetBlank.as

ExtendSetBlank.as

import flash.text.*;
class ExtendSetBlank extends SetBlank{
    function ExtendSetBlank(){
        trace("abc")
    }
}

I can see the trace function working but the method which sets the text field to blank is now working. I can’t figure out where I am wrong.

Please help.