Remote Desktop Gateway - Event 304/Error "23005"

Hi,

I am tearing my hair out.  I have a RD Gateway server that is pointing towards a RD Farm.  I cannot connect to it using the Gateway.  I keep getting the the following error in the TerminalServices-Gateway Operational log:

Log Name:      Microsoft-Windows-TerminalServices-Gateway/Operational
Source:        Microsoft-Windows-TerminalServices-Gateway
Date:          10/7/2014 10:56:02 AM
Event ID:      304
Task Category: (3)
Level:         Warning
Keywords:      (16777216)
User:          NETWORK SERVICE
Computer:      XXXXXXXXXXX.wbc.local
Description:
The user "XXXXXX", on client computer "XXX.XXX.XXX.XXX", met connection authorization policy and resource authorization policy requirements, but could not connect to resource "SyteLine.wbc.local". The following error occurred:"23005".
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-TerminalServices-Gateway" Guid="{4D5AE6A1-C7C8-4E6D-B840-4D8080B42E1B}" />
    <EventID>304</EventID>
    <Version>0</Version>
    <Level>3</Level>
    <Task>3</Task>
    <Opcode>44</Opcode>
    <Keywords>0x4000000001000000</Keywords>
    <TimeCreated SystemTime="2014-10-07T15:56:02.952172000Z" />
    <EventRecordID>183</EventRecordID>
    <Correlation />
    <Execution ProcessID="2428" ThreadID="3140" />
    <Channel>Microsoft-Windows-TerminalServices-Gateway/Operational</Channel>
    <Computer>WBC-SLGW-01.wbc.local</Computer>
    <Security UserID="S-1-5-20" />
  </System>
  <UserData>
    <EventInfo xmlns="aag">
      <Username>XXXXXXXXXXXXX</Username>
      <IpAddress>XXX.XXX.XXX.XXX</IpAddress>
      <AuthType>
      </AuthType>
      <Resource>SyteLine.wbc.local</Resource>
      <ErrorCode>23005</ErrorCode>
    </EventInfo>
  </UserData>
</Event>

Any ideas?  Lots of googling has not helped

Thanks