Possibly your query could be on the quantum of the incentive. However, three important factors precede before disbursement of the incentive. These are:
a) Do you measure what deserves to be measured
b) Do you measure accurately whatever you measure and
c) People were paid on the one hand but organisation suffered losses on the another. Management or HR is unaware of those losses
Unless you have clear answers to the above questions, my humble recommendation is not to start the performance incentive plan. Else it would be faulty one. It's side effects you will come know but much later.