Merchant SDK PHP

Question

I am using the following payment gateway integration from paypal

https://github.com/paypal/merchant-sdk-php

1. Authorisation of creditcard works fine , the response object gives me the authorisation ID
   

   DoDirectPaymentResponseType Object ( [Amount] =>
   [AVSCode] => A
   [CVV2Code] => M
   [TransactionID] => 77590473BS040440N
   [TransactionPendingReason] =>
   [PendingReason] =>
   [PaymentStatus] =>
   [FMFDetails] =>
   [ThreeDSecureResponse] =>
   [PaymentAdviceCode] =>
   [Timestamp] => 2024-01-18T07:29:14Z [Ack] => Success
   [CorrelationID] => 8db154f55cecc
   [Errors] =>
   [Version] => 204.0
   [Build] => 56068150 )

2. Capture of the Authorisation works fine, I pass the authorisation ID to capture the payment.

Problem: I dont know why I dont get the payment ID (or transaction ID) of the completed transaction.

See below the response text

(
    [PaymentTransactionDetails] => 
    [ThreeDSecureDetails] =>
    [Timestamp] => 2024-01-18T03:35:43Z
    [Ack] => Success
    [CorrelationID] => 8e94f669b1481
    [Errors] => 
    [Version] => 204.0
    [Build] => 57991821
)

DoCaptureResponseType Object
( 
[DoCaptureResponseDetails] =>
[Timestamp] => 2024-01-18T03:40:13Z
[Ack] => Failure 
[CorrelationID] => 37f66a0e63bdf
[Errors] => 
[Version] => 204.0
[Build] => 58313039 )

The completed Transaction cannot be refunded or reversed because I donot have transaction ID!
Can someone help please?