How to continuely index a cell in a loop

I am trying to create and inventory that continues to index the second column everytime it runs throught the loop. It is apart of a pushbutton call back so that everytime it is clicked it is suppose to run through the loop. It will run through but it stops indexing even after I click the push button multiple times.

function pushbutton4_Callback(hObject, eventdata, handles) % hObject handle to pushbutton4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

global G

    if (exist('Inventory1.mat','file') == true)
    load('Inventory1.mat')
    found = false
    for InventoryIndex= 1: size(Inventory1,1)
        if compare(G,Inventory1{InventoryIndex,1})
            %if match we found a match and need to increment how many we have
            %fou
            Inventory1{InventoryIndex,2} = Inventory1{InventoryIndex,2} + 1 
            found= true
        else
            %keep looking
        end;
    end;
    if (found== false)
        if (InventoryIndex == size(G,1))
            Inventory1{InventoryIndex + 1, 1} = G
            Inventory1{InventoryIndex + 1, 2} = 1
        end;
    end;
else
   Inventory1{1,1}= G
   Inventory1{1,2}= 1
end;

save('Inventory1.mat','Inventory1')

[Jan]

exist('Inventory1.mat','file') == true is not correct. exist() does not answer true or false but a number from 0 to 8. So better use: exist('Inventory1.mat','file') ~= 0 .

What is the problem of your code?