Event ID 2513

Log Name:      Directory Service
Source:        Microsoft-Windows-ActiveDirectory_DomainService
Date:          10/23/2012 4:14:52 PM
Event ID:      2513
Task Category: DS RPC Client
Level:         Error
Keywords:      Classic
User:          ANONYMOUS LOGON
Computer:      MAIL.Tower-ieg.com.jo
Description:
Attempting to set the desired authentication protocol for a connection to the following DSA failed.
DSA:
a01f45bb-1e5d-46c5-bef0-94f674bd1037._msdcs.Tower-ieg.com.jo

Additional Data:
Error:
1747 The authentication service is unknown.

Event Xml:

  <System>
    <Provider Name="Microsoft-Windows-ActiveDirectory_DomainService" Guid="{0e8478c5-3605-4e8c-8497-1e730c959516}" EventSourceName="NTDS Replication" />
    <EventID Qualifiers="49152">2513</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>22</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8080000000000000</Keywords>
    <TimeCreated SystemTime="2012-10-23T14:14:52.978163700Z" />
    <EventRecordID>6185</EventRecordID>
    <Correlation />
    <Execution ProcessID="644" ThreadID="808" />
    <Channel>Directory Service</Channel>
    <Computer>MAIL.Tower-ieg.com.jo</Computer>
    <Security UserID="S-1-5-7" />
  </System>
  <EventData>
    <Data>a01f45bb-1e5d-46c5-bef0-94f674bd1037._msdcs.Tower-ieg.com.jo</Data>
    <Data>The authentication service is unknown.</Data>
    <Data>1747</Data>
  </EventData>
</Event>

Please I need your help urgent.

Thanks in Advance

Ibrahim