I've just bought your plugin PAy per vew but I have

Hi

I've just bought your plugin PAy per vew but I have a problem with paypall.

There was a problem connecting to PayPal to setup your purchase. Please try again. ?10401 – Transaction refused because of an invalid argument. See additional error messages for details. – Order total is invalid.
?10431 – Transaction refused because of an invalid argument. See additional error messages for details. – Item amount is invalid.

I don't know why.

Could you help me

Thanks