AS3 Adding Bitmaps from the library

programming flash
1

I hope someone can see what i am doing wrong here.
I have a jpg in the library with a class name Test(autogenerated) and my code

var bmp:Bitmap=new Bitmap();
			bmp.bitmapData=new Test();
			addChild(bmp);

Gives this error

Argument count mismatch on Test$iinit(). Expected 2, got 0.

I have found i can put any too parameters into the constructor and it works
eg/

bmp.bitmapData=new Test("we",2);

I think i am missing something obvious but just not sure what.
(I tried the code senocular posted in the AS3 tips and also needed to add the 2 arguments)