The transaction returned an Error.

Request

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://fedex.com/ws/track/v12"><SOAP-ENV:Body><ns1:TrackRequest><ns1:WebAuthenticationDetail><ns1:ParentCredential><ns1:Key/><ns1:Password/></ns1:ParentCredential><ns1:UserCredential><ns1:Key>dOFzTHhjdgbiJwuT</ns1:Key><ns1:Password>HrWJqYGUVFEmZxPQqPSMSiYqg</ns1:Password></ns1:UserCredential></ns1:WebAuthenticationDetail><ns1:ClientDetail><ns1:AccountNumber>809163288</ns1:AccountNumber><ns1:MeterNumber>110691611</ns1:MeterNumber></ns1:ClientDetail><ns1:TransactionDetail><ns1:CustomerTransactionId>*** Track Request using PHP ***</ns1:CustomerTransactionId></ns1:TransactionDetail><ns1:Version><ns1:ServiceId>trck</ns1:ServiceId><ns1:Major>12</ns1:Major><ns1:Intermediate>0</ns1:Intermediate><ns1:Minor>0</ns1:Minor></ns1:Version><ns1:SelectionDetails><ns1:PackageIdentifier><ns1:Type>TRACKING_NUMBER_OR_DOORTAG</ns1:Type><ns1:Value/></ns1:PackageIdentifier></ns1:SelectionDetails></ns1:TrackRequest></SOAP-ENV:Body></SOAP-ENV:Envelope>

Response

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"><SOAP-ENV:Header/><SOAP-ENV:Body><TrackReply xmlns="http://fedex.com/ws/track/v12"><HighestSeverity>ERROR</HighestSeverity><Notifications><Severity>ERROR</Severity><Source>trck</Source><Code>900011</Code><Message>The package identifier value is missing or invalid.</Message><LocalizedMessage>The package identifier value is missing or invalid.</LocalizedMessage></Notifications><TransactionDetail><CustomerTransactionId>*** Track Request using PHP ***</CustomerTransactionId></TransactionDetail><Version><ServiceId>trck</ServiceId><Major>12</Major><Intermediate>0</Intermediate><Minor>0</Minor></Version></TrackReply></SOAP-ENV:Body></SOAP-ENV:Envelope>