My agent credits me a percentage of his commission when I buy and sell. When I enter the credit as a negative number under buying costs, the profit is correct only if the buying cost is greater than the credit.

For example, let's say I have a buying cost of $2000 and a credit of $500. Then it increases the profit by $1500, which is correct.

For another example, let's say the buying cost is still $2000, but my credit is now $5000. The calculation of the profit is then incorrect. The profit should increase by $3000. But instead, it decreases the profit by $3000.

Will you please correct the calculation error?