I'm getting the following error when using my Sandbox Credentials using the Sample Code. This is only happening when I'm trying to do PayPal Express Checkout. My API Transaction Key and Login credentials work for other transactions.

Is this due to the Sandbox Maintenance that is scheduled for today at 6:00pm Pacific? 

Any help would be appreciated. Thanks!

E00027 : The transaction was unsuccessful. 57 : An error occurred during processing. Please try again

<?xml version="1.0" encoding="utf-8"?> 
<createTransactionResponse xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="AnetApi/xml/v1/schema/AnetApiSchema.xsd">
  <messages>
    <resultCode>
      Error
    </resultCode>
    <message>
      <code>
        E00027
      </code>
      <text>
        The transaction was unsuccessful.
      </text>
    </message>
  </messages>
  <transactionResponse>
    <responseCode>
      3
    </responseCode>
    <rawResponseCode>
      0
    </rawResponseCode>
    <transId>
      2254998933
    </transId>
    <refTransID />
    <transHash>
      0573D45B85D937B5D90398C864BDF8F7
    </transHash>
    <testRequest>
      0
    </testRequest>
    <entryMode>
      Keyed
    </entryMode>
    <accountType>
      PayPal
    </accountType>
    <errors>
      <error>
        <errorCode>
          57
        </errorCode>
        <errorText>
          An error occurred during processing.  Please try again.
        </errorText>
      </error>
    </errors>
  </transactionResponse>
</createTransactionResponse>