Paypal geteway Internal Error (#10001: Internal Error)

Question

This is Debug log dump.
But I have no idea what's going on.

Test in paypal sandbox mode.
Check out with Paypal express.

2014-05-01T06:30:17+00:00 DEBUG (7): Array
(
    [url] => https://api-3t.sandbox.paypal.com/nvp
    [ManagePendingTransactionStatus] => Array
        (
            [TRANSACTIONID] => 4GB13868J7284553K
            [ACTION] => Accept
            [METHOD] => ManagePendingTransactionStatus
            [VERSION] => 72.0
            [USER] => ****
            [PWD] => ****
            [SIGNATURE] => ****
            [BUTTONSOURCE] => Varien_Cart_EC
        )

    [response] => Array
        (
            [TRANSACTIONID] => 4GB13868J7284553K
            [STATUS] => The Status of the transaction after running the your action (accept/deny) is:Unable To Determine
            [TIMESTAMP] => 2014-05-01T06:30:11Z
            [CORRELATIONID] => c38b1544405a1
            [ACK] => Failure
            [VERSION] => 72.0
            [BUILD] => 10800277
            [L_ERRORCODE0] => 10001
            [L_SHORTMESSAGE0] => Internal Error
            [L_LONGMESSAGE0] => Internal Error
            [L_SEVERITYCODE0] => Error
        )

    [__pid] => 553023
)

exception.log

2014-04-30T06:08:43+00:00 ERR (3): 
    exception 'Mage_Core_Exception' with message 'PayPal NVP gateway errors: Internal Error (#10001: Internal Error). Correlation ID: e472a9b1d2146. Version: 72.0.' in /home/sokietec/public_html/app/Mage.php:580
    Stack trace:
    #0 /home/sokietec/public_html/app/code/core/Mage/Paypal/Model/Api/Nvp.php(1050): Mage::exception('Mage_Core', 'PayPal NVP gate...')
    #1 /home/sokietec/public_html/app/code/core/Mage/Paypal/Model/Api/Nvp.php(1011): Mage_Paypal_Model_Api_Nvp->_handleCallErrors(Array)
    #2 /home/sokietec/public_html/app/code/core/Mage/Paypal/Model/Api/Nvp.php(773): Mage_Paypal_Model_Api_Nvp->call('ManagePendingTr...', Array)
    #3 /home/sokietec/public_html/app/code/core/Mage/Paypal/Model/Pro.php(311): Mage_Paypal_Model_Api_Nvp->callManagePendingTransactionStatus()
    #4 /home/sokietec/public_html/app/code/core/Mage/Paypal/Model/Express.php(406): Mage_Paypal_Model_Pro->reviewPayment(Object(Mage_Sales_Model_Order_Payment), 'accept')
    #5 /home/sokietec/public_html/app/code/core/Mage/Sales/Model/Order/Payment.php(932): Mage_Paypal_Model_Express->acceptPayment(Object(Mage_Sales_Model_Order_Payment))
    #6 /home/sokietec/public_html/app/code/core/Mage/Sales/Model/Order/Payment.php(896): Mage_Sales_Model_Order_Payment->registerPaymentReviewAction('accept', true)
    #7 /home/sokietec/public_html/app/code/core/Mage/Adminhtml/controllers/Sales/OrderController.php(240): Mage_Sales_Model_Order_Payment->accept()
    #8 /home/sokietec/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_Sales_OrderController->reviewPaymentAction()
    #9 /home/sokietec/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('reviewPayment')
    #10 /home/sokietec/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
    #11 /home/sokietec/public_html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
    #12 /home/sokietec/public_html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
    #13 /home/sokietec/public_html/index.php(87): Mage::run('', 'store')
    #14 {main}