klarna checkout not working

[piekielko]

when i select a payment (KLARNA checkout) in my cart i get an error:

Fatal error: Class 'Klarna_Checkout_Order' not found in /www/plugins/vmpayment/klarnacheckout/klarnacheckout.php on line 323

Line 323:

Code Select Expand

             $cartIdInTable = $this->storeCartInTable($cart);
if ($this->method->server == 'beta') {
Klarna_Checkout_Order::$baseUri = 'https://checkout.testdrive.klarna.com/checkout/orders';
} else {
Klarna_Checkout_Order::$baseUri = 'https://checkout.klarna.com/checkout/orders';
}

Error is apparent in: VM 2.0.26.
In the last stable version (VM 2.6) i have blank screen - this payment not working.

My Joomla version: 2.5.19