issue with WinRM : kerberos authGSSClientStep failed (None)

Error message :
2014-09-10 08:29:22,718 ERROR zen.PythonClient: Error on 192.168.1.20: kerberos authGSSClientStep failed (None).
2014-09-10 08:29:22,718 INFO zen.PythonClient: Python client finished collection for 192.168.1.20
2014-09-10 08:29:22,719 WARNING zen.ZenModeler: The plugin zenoss.winrm.CPUs returned no results.

I've followed the steps on the wiki for setting up winRM

zWinKDC = server.domain.local (I've also tried IP address)
zWinRMServerName = 192.168.1.20 (I've also tried name.domain.local)
zWinRMPort = 5985
zWinRMUser = user@domain.local (confirmed that lower case is how it is displayed in A/D)
zWinScheme = http

I believe I've got the WinRM Settings set properly :

Config
MaxEnvelopeSizekb = 150
MaxTimeoutms = 60000
MaxBatchItems = 32000
MaxProviderRequests = 4294967295
Client
NetworkDelayms = 5000
URLPrefix = wsman
AllowUnencrypted = false
Auth
Basic = true
Digest = true
Kerberos = true
Negotiate = true
Certificate = true
CredSSP = false
DefaultPorts
HTTP = 5985
HTTPS = 5986
TrustedHosts
Service
RootSDDL = O:NSG:BAD:P(A;;GA;;;BA)S:P(AU;FA;GA;;;WD)(AU;SA;GWGX;;;WD)
MaxConcurrentOperations = 4294967295
MaxConcurrentOperationsPerUser = 15
EnumerationTimeoutms = 60000
MaxConnections = 25
MaxPacketRetrievalTimeSeconds = 120
AllowUnencrypted = true [Source="GPO"]
Auth
Basic = true [Source="GPO"]
Kerberos = true [Source="GPO"]
Negotiate = true [Source="GPO"]
Certificate = false
CredSSP = false
CbtHardeningLevel = Relaxed
DefaultPorts
HTTP = 5985
HTTPS = 5986
IPv4Filter = * [Source="GPO"]
IPv6Filter [Source="GPO"]
EnableCompatibilityHttpListener = false
EnableCompatibilityHttpsListener = false
CertificateThumbprint
Winrs
AllowRemoteShellAccess = true [Source="GPO"]
IdleTimeout = 7200000
MaxConcurrentUsers = 5
MaxShellRunTime = 2147483647
MaxProcessesPerShell = 2147483647 [Source="GPO"]
MaxMemoryPerShellMB = 150
MaxShellsPerUser = 2147483647 [Source="GPO"]

I'm at a loss here and don't know which direction I should be troubleshooting. Halp