dip notation not working - Android

Question

Okay, from what I understand if I say <EditText android:layout_width="120dip" /> (With ID, height and all that good stuff added), it's supposed to create a text field that occupies 3/4th of the screen independent of the resolution of the screen.

So why do I get a tiny little text box, with a width of not more than 20 real pixels on an Android Lvl 4 simulator?

Am I missing something fairly obvious?

Thanks,
Teja.