Go to the Base tab.
In the 'Options' area, make sure that the Combination wizard check box is selected.
Go to the Actions tab.
The two action categories – 'Permanent' and 'Imposed' loads – are listed according to the definition when you created the load cases (see the LC2: Imposed Load on Lower Slab image).
Select the second action – A2 Imposed loads. The 'Action type' is 'Simultaneously': All load cases of that action category can be effective at the same time (unlike wind load cases, for example).
On the Assignment subtab, you can see that LC2 through LC4 are allocated to that category.
