Sum of two case statements for item quantity?

So I have two simple case statements that help me see inventory by location.  When separating the formulas, I can see the proper numbers in each column.

Formula (Numeric) --> CASE WHEN {inventorylocation.namenohierarchy}= 'Los Angeles' THEN {locationquantityavailable} END

Formula (Numeric) --> CASE WHEN {inventorylocation.namenohierarchy}= 'Phoenix' THEN {locationquantityavailable} END

But when I try to add the two case statements together, I only get a blank value. 

(CASE WHEN {inventorylocation.namenohierarchy}= 'Los Angeles' THEN {locationquantityavailable} END) + (CASE WHEN {inventorylocation.namenohierarchy}= 'Phoenix' THEN {locationquantityavailable} END)

In case you are wondering why I do not pull the "Available" column, we have additional warehouses under the one subsidiary that I need to exclude that would have otherwise been included when searching the "Available" field.