Process flow decision seems to ignore the outcome

I have a question regarding the decision task. I created a small process flow that needs to execute the create wallet task based on whether or not a variable has been set. (see diagram) 

In order to get this result I have implemented a decision activity and corresponding process functionality. But no matter the outcome it always seems to execute both tasks. 

1declare @has_wallet bit = 0;
2
3set @has_wallet = (
4        select coalesce((
5                    select 1
6                    from wallet_employee we
7                    where we.location_id = @location_id
8                        and we.employee_id = @employee_id
9                    ), 0)
10        )
11
12if @has_wallet = 1
13begin
14    -- wallet available
15    set @has_wallet_execute_task_create_wallet = null;
16    set @has_wallet_execute_task_create_employee_lunch_transaction = 10;
17end
18else if @has_wallet = 0
19begin
20    -- no wallet available
21    set @has_wallet_execute_task_create_wallet = 10;
22    set @has_wallet_execute_task_create_employee_lunch_transaction = null;
23end

I've tried setting them to null, 0 and -1 but it doesn't seem to matter. I assume that I've probably done something wrong. So here's the question, how do I get the decision to work properly?