I don't know what i was doing wrong, but i did it from the beginning and ended with everything ok
Thanks a lot for the help!

Hi Gaieus,
Thanks for the answer!
But i'm still having trouble withe the linear arrays.
As soon as i copy the shelf and click on the destned point for that copied item, the copied item is selected and the riginal deselected. As i try to make copies or to divid it evenly by typing the numbers, if i'm doing it while moving the copied shelf it tells me abou invalid length. If i do it after, nothing appears on the bottom left corner (measurements/length) on my google sketchup, where it stays unusable to enter any number to divide my copy.
Any idea of what is happenning?

Hello Friends,
I made a group on sketchup to model a cabinet for my living room.
After offsetting and everything, i made a rectangle to make my shelf
component. Following some instructions on the youtube video
http://www.youtube.com/watch?v=Kae7uZxyOzQ&eurl=http%3A%2F%2Fwww%2Eyoutube%2Ecom%2Fuser%2F4sketchupgo2school&feature=player_profilepage
; i'm trying to evenly divide the shelves inside my cabinet.
How do i do that?