Problem with Extrude
 

I'm quite new to maya and I have a problem with extruding multiple faces.

when I select multiple faces like in the picture below
http://onfinite.com/libraries/908525/fcf.jpg

and select extrude the following thing happens:
http://onfinite.com/libraries/908526/c6b.jpg

when I extrude this is the result...
http://onfinite.com/libraries/908527/b28.jpg

is there a way to extrude multiple faces without maya adding the the faces in the middle :confused:

i think the problem is that there are also faces on the edges
if you deselect the ones i put a red circle around it will work

Polygons > Tool Options > Keep Faces Together

thanks guys!! :attn: