Need Help: Rapidcart Pro and Coupon Code error with PayPal

Whenever i use coupon code on RapidCart Pro and put in a negative number for the discount i get an error url 400 message and i can not finalize payment as it won’t take me to PayPal account. Does NOT happen if I have a positive number or no coupon at all.

I couldn’t reproduce the problem on our test servers.
Coupon codes work correctly with PayPal here.

We need further details to find where the problem is with your configuration.
I’ve sent you instructions to get PayPal logs in our support system.