PaymentActionNotInitiated when do Express Checkout

I play Sandbox to put Express Checkout to my site. Eveyrthing goes fine: user clicks payment button, goes redirected to paypal, logs in with Sandbox buyer's credentials getting to his sandbox page, clicks Continue button and finally goes redirected back to my site just click Confirmation button. But nothing happens to funbdings of Sandbox Seller and Byer test accounts. I revealed that both GetExpressCheckoutDetails and DoExpressCheckoutPayment contain CHECKOUTSTATUS=PaymentActionNotInitiated. According to Paypal integration - GetExpressCheckout...Read more