An error occurred when we tried to contact the payment processor. 10401

[djenojado]

Hi!

Zen-Cart 1.3.8
I installed paypal express and got this error -->

An error occurred when we tried to 
contact the payment processor. Please try again, 
select an alternate payment method, or contact 
the store owner for assistance. (10401) 10401 
Transaction refused because of an invalid argument. 
See additional error messages for details. 
- Order total is invalid.

I installed paypal ipn. Now, my store redirectet to paypal, but I can see the total price is 0.

I think I got the paypal express error because the price is 0. I don't know.

I hope someone have some tip for me! :)

Thanks

Br,
Eno