It's seems you missed messageLogging
element. MSDN link.
<system.serviceModel>
<diagnostics>
<messageLogging
logEntireMessage="true"
logMalformedMessages="true"
logMessagesAtServiceLevel="true"
logMessagesAtTransportLevel="false"
maxMessagesToLog="3000"
maxSizeOfMessageToLog="20000"/>
</diagnostics>
</system.serviceModel>