vCAC 6 - The attached endpoint cannot be found. (vSphere 5.0)

We are using VirtualCenter 5.0 U1. I have tried again and again to connect vSphere agent with existing VC.

All services are running on same Windows 2008 R2 server. Ping works, telnet with Port 443 works, Firewall is actually turned of.

Endpoint definition is identically to a well running vCAC 5.2 config.

[13.01.2014 14:07:58] [Info]: Process running in x64 mode

[13.01.2014 14:07:58] [Info]: Created VRM Core Agent Service

[13.01.2014 14:07:58] [Info]: Starting VRM Core Agent Service

[13.01.2014 14:07:58] [Info]: Version: 6.0.0.2608

[13.01.2014 14:07:58] [Info]: Retrieving VRMCommunication Definition

[13.01.2014 14:07:58] [Info]: VRMCommunication : DynamicOps.Vrm.Agent.Core.Communication.VRMCommunication

[13.01.2014 14:07:58] [Info]: Retrieving WorkitemCache Type Definition

[13.01.2014 14:07:58] [Info]: WorkitemCache Type : DynamicOps.Vrm.Agent.Common.Utils.WorkitemSerializer

[13.01.2014 14:07:58] [Debug]: Retrieving Agent Type Definition

[13.01.2014 14:07:58] [Debug]: Agent Type : DynamicOps.Vrm.Agent.vSphere.VSphereAgentService

[13.01.2014 14:07:58] [Info]: Checking Agent Configuration Sanity

[13.01.2014 14:07:58] [Info]: VRM AgentName: vSphereAgent

[13.01.2014 14:07:58] [Info]: VRM Url: https://vaciaas01.local/VMPS2

[13.01.2014 14:07:58] [Info]: Workitem CacheFile: C:\Program Files (x86)\VMware\vCAC\Agents\vSphereAgent\temp\WorkItems.bin

[13.01.2014 14:07:58] [Info]: Workitem Max Threads: 10

[13.01.2014 14:07:58] [Info]: Workitem Thread Interval: 00:00:15

[13.01.2014 14:07:58] [Info]: Workitem Retrieval Count: 3

[13.01.2014 14:07:58] [Info]: PingTimer Interval: 00:01:00

[13.01.2014 14:07:58] [Info]: StateTimer Interval: 01:00:00

[13.01.2014 14:07:58] [Info]: Active Queue Size: 10

[13.01.2014 14:07:58] [Info]: TES disabled

[13.01.2014 14:07:58] [Info]: Starting WorkItemService

[13.01.2014 14:07:58] [Debug]: Started WorkItemService

[13.01.2014 14:07:58] [Info]: Starting CheckTargetAliveService

[13.01.2014 14:07:58] [Debug]: Started CheckTargetAliveService

[13.01.2014 14:07:58] [Info]: Starting HostStateReportService

[13.01.2014 14:07:58] [Info]: HostStateReportService has been disabled in the configuration!

[13.01.2014 14:07:58] [Info]: Starting PingService

[13.01.2014 14:07:58] [Debug]: Started PingService

[13.01.2014 14:08:58] [Debug]: Starting Ping Report

[13.01.2014 14:08:58] [Debug]: This exception was caught:

System.NullReferenceException: The attached endpoint 'vcenter.local:443' cannot be found.

   at DynamicOps.Vrm.Agent.vSphere.RepositoryServiceProvider.GetManagementEndpoint(String name)

   at DynamicOps.Vrm.Agent.vSphere.VSphereHypervisorData.FetchCredentials()

   at DynamicOps.Vrm.Agent.vSphere.VSphereHypervisorServiceProvider.GetHypervisorData()

   at DynamicOps.Vrm.Agent.vSphere.VSphereHypervisorServiceProvider.GetComputeResources(ManagementEndpoint managementEndpoint)

   at DynamicOps.Vrm.Agent.vSphere.VSphereAgentService.GetHostClusterList()

   at DynamicOps.Vrm.Agent.Core.VRMCoreAgent.SendPingReport()

   at DynamicOps.Vrm.Agent.Core.CoreAgentBase.SendPingReportLoop(Object sender, ElapsedEventArgs e)

[13.01.2014 14:08:58] [Error]: <?xml version="1.0" encoding="utf-16"?>

<boolean>false</boolean>

Could anybody help with hints for troubleshooting?

thx

Sulihari