Apps Margin Property of an ImageView in code

[totally_insane]

Hey,
How can i set the layout_margin property of an ImageButton in code?

Heres what i've got:

	ImageButton ib = (ImageButton) findViewById(R.id.btn_learn);
	MarginLayoutParams mlp = new MarginLayoutParams(ib.getLayoutParams());
	
	if(newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE)
	    mlp.setMargins(0, 20, 0, 0);
	else
	    mlp.setMargins(0, 100, 0, 0);
	
	ib.setLayoutParams(mlp); // ERROR HERE

Well, theres an error - classcastException - sure..
The setLayoutParams wants an "LayoutParams" and im giving a "MarginLayoutParams".
Well that was finally what I tried.

Any ideas how i can make that working?