NSTableView with alternating rows

Hi All!

I have a problem creating NSTableView with alternating rows even  
though in Inspector I have choosen that option and in Interface  
builder I see alternating rows (white-blue-white-blue background of  
table). The problem is that when I use "Simulate Interface" or compile  
the code, alternating rows are gone and I have just plain boring white  
background.

Any help with this would be deeply appreciated.

Ivan