Checkout strange message

[Guest]

I have a module for credit card payment already installed.

It seems to work fine, I create a cart, pay articles, and then I go to page CHECKOUT_PROCESS.PHP, but I see message ' NOK '. white window with letters NOK. I cannot find this message in the source.

 

If I do the same thing with another payment method (ex. funds transfer ) , everything is OK, cart empty and shows the right message to the user.

 

Any idea?

 

TIA

Jam