Incorrect payment sum or payment flag?

Question

1C-Bitrix

The "payment.receive" component refuses to update the order status when receiving information about its payment from the "PayMaster" service. The page with the component is called, and it receives the $_POST array with the "LMI_PAYMENT_AMOUNT" parameter, which contains the value of the amount paid. When trying to change the status, the "serviceResult" object returns the following error:

Incorrect payment sum or payment flag

Also, I didn't find the "isCorrectSum()" method in the "PayMasterHandler" handler (sale/handlers/paysystem/paymaster/handler.php). Maybe that's the thing, I don't know.
Tell me what could be the problem.