How to change a resource icon in a imageview with another resource icon

How to change a resource icon in a imageview with another resource icon

I have been reading some post about the change image in a imageview. But
all people ask for change a imageview with a custom image, and I want to
change with a system image.
I make this.
ledicon.setImageDrawable(getResources().getDrawable(R.drawable.presence_busy));
But eclipse says me that presence_busy is not recognized. Why? I am using
presence_online in the XML file,
android:src="@android:drawable/presence_online" and all works perfectly.
Thanks for your advices.