I have created a Select Expert formula to select warehouses and items within warehouses.  The problem is if I select 'ALL' warehouses and then try to select only discrete values for the Item, I get all items.  If I select one or more discrete Warehouses and also discrete items, I get only the discrete items in the discrete warehouses.

Why does selecting 'ALL' warehouses give me also 'ALL' items when I only want discrete items?
 
If {?Warehouse}= 'ALL'
Then {Relsc.Lagerort} like '*'
Else {RelSc.Lagerort} = {?Warehouse} and
if {?Item} = 'ALL'
Then {RELSC.ARTIKELNR} like '*'
Else {RELSC.ARTIKELNR} = {?Item}