How to add delievry fee based on sales order value

REQUIREMENT:
Based on the Order total (excluding Tax), a specific Customer should be charged a One-time delivery Fee (which is to be added as a new Order line with a Non stockable item and is only billed).

 

We created a Pricing Promotion with 2 rules, one with >280 EUR and the other one with <50 EUR scenarios. As it is clear from the screenshots, for each of these cases, we added an item with some value on the Benefit

 

ISSUE:
As per the setup, our expectation is whenever the Promotion eligibility conditions are met, this new line gets added. But in reality, this new line is getting added but with charge as 0, as it is applying a 100% discount to the value.