Error while using discount voucher

[ksehmi79]

HI,

 

I am using Presta 1.6.0.9

&
PayPal USA, Canada v1.3.8 

If i make a purchase and checkout using paypal everything works fine BUT if i use discount coupon then i receive the following error:
 

Unexpected payment error

Unfortunately, an error occured while communicating with PayPal.

Short Error Message: Transaction refused because of an invalid argument. See additional error messages for details.
Detailed Error Message: The totals of the cart item amounts do not match order amounts.
Error Code: 10413
Please contact our Customer service and mention this error code to get this issue resolved.

Our website is : sdigital.co 
Voucher Code: FB20-0715

Any help will be appreciated...