Excel: Logistics cost optimization with constrained destination points?

We are trying to run a model, which will help us minimize the overall logistics cost. We have different type of vehicles available in the fleet, each with a different capacity and different tariff.

As a result of this solution, we want to reach an outcome, where not only the logistics cost incurred by me is the lowest, but at the same time, I want to ensure that most of number of vehicles used by me are touching two drop points. All drop points available can be assumed to be equidistant for the sake of simplicity. The way we have modeled this problem is not helping because solver is throwing an error that we are trying to solve a NSP (Non Smooth Problem)

Objective fn: sum(derived_cost,criteria(Combination>0))

VehicleConfiguration.png
Optimization.png

Will be grateful if someone can help.