Extrude Face

Hello!

I am a new Maya 8.5 user. I try do learn Maya via video-tuts and online tuts.
When I came to modelling polygon objects, there seems to be a problem:

First I draw a poly cube.
Then I change to faces and select the upper face.
When I click on "extrude face" I can only extrude along x and z axis, not along y. The cube is simply doing nothing when I pull at the y-Axis arrow of the extrude-modificator. In every tutorial i know the cube extrudes in height (y) and the side faces are then automatically split in two faces (original one and extruded height), but mine doesn't.

Can anybody help me with this problem?

ThanX, netrunner

Topic closed!

I figured out, that I have to right-klick into the modificator symbol first and then drag to get a blue cube where the blue Y-Axis-Arrow is.
Only then I can also drag / extrude the face along the Y-Axis.

Not very logical, but works!