This article details a technique to increase the probability of spending a specific budget on a given line item.
Note first that due to the nature of real time bidding on open exchanges, it can never be guaranteed that a line item or campaign fully spends its budget. Plus, the advanced targeting settings at the line item level can make it more difficult to identify proper inventory sources on which to bid.
Context
By default, the campaign budget will be optimized by Ad360 to maximize your campaign goal.
Hence the budget allocation between line items will not be set in stone, but rather optimized in real time by Ad360 Artificial Intelligence. This enables to spend more on line items that deliver better results and ensures that the campaign budget will be spent optimally to maximize your campaign outcomes.
However, it also means that you can't guarantee that a certain line item in a campaign will be allocated budget, in case Ad360 Artificial Intelligence algorithms consider that another line item would get better results.
For more information on how the budget allocation works between line items of a campaign, you can read this Help Center article: Budget Allocation between Line Items in a Campaign
Objective
In some cases though, you may want to increase chances that a certain line items gets allocated budget.
Solution
The best way to ensure that more budget will be allocated to a line item is to isolate it by creating a new campaign with only 1 line item. In this new campaign, put as the campaign budget and line item budget the amount that you would like to spend on this line item.
Since there won't be other line items in the campaign, this ensures that the line item will be allocated 100% of the campaign's budget (note again as previously stated that this does NOT however guarantee full delivery).
Keep in mind though that this may affect negatively your results. Indeed, if the line item was not allocated budget before in the campaign, it means that the Ad360 AI considered that the budget was producing more results when spent on other line items of the campaign.