Next, the allocation analysis tells you that "0 impressions are allocated to 3 line items, which is 0.00% of the projected traffic". This may sound strange, but the reason is that none of the three line items currently taking up space for this site have any objectives (impressions, clicks etc) registered. Let's say that one of the three line items had an impression objective of 100,000 impressions, was targeted to this ad unit only and had start and end dates equal to the ones you chose, then the message could be "100,000 impressions are allocated to 3 line items, which is 43.29% of the projected traffic".