Using Create an Appointment gives Error "ErrorFolderNotFound" when using impersonation

We have impersonation and permissions set on a service account to create Outlook appointments but the workflow errors with "ErrorFolderNotFound" when using the service account.

 The ULS logs

01/10/2012 12:48:54.43  w3wp.exe (0x13F4)                        0x1204 Windows SharePoint Services    Workflow Infrastructure        88xr Unexpected WinWF Internal Error, terminating workflow Id# a3af8d4c-998d-443e-bf73-68262131e164 
01/10/2012 12:48:54.43  w3wp.exe (0x13F4)                        0x1204 Windows SharePoint Services    Workflow Infrastructure        98d4 Unexpected System.Exception: Task item failed with response code ErrorFolderNotFound     at Nintex.Workflow.Activities.ExchangeCreateItemActivity.Execute(ActivityExecutionContext executionContext)     at System.Workflow.ComponentModel.ActivityExecutor`1.Execute(T activity, ActivityExecutionContext executionContext)     at System.Workflow.ComponentModel.ActivityExecutor`1.Execute(Activity activity, ActivityExecutionContext executionContext)     at System.Workflow.ComponentModel.ActivityExecutorOperation.Run(IWorkflowCoreRuntime workflowCoreRuntime)     at System.Workflow.Runtime.Scheduler.Run() 
01/10/2012 12:48:57.01  OWSTIMER.EXE (0x0730)                    0x0758 Windows SharePoint Services    E-Mail                         6871 Information The Incoming E-Mail service has completed a batch.  The elapsed time was 00:00:00.  The service processed 0 message(s) in total. 
01/10/2012 12:48:56.19  w3wp.exe (0x13F4)                        0x0304 CMS                            Publishing                     8ztg Medium   Got List Item Version, but item was null. 
01/10/2012 12:48:56.19  w3wp.exe (0x13F4)                        0x0304 CMS                            Publishing                     8ztg Medium   Got List Item Version, but item was null. 
01/10/2012 12:48:56.19  w3wp.exe (0x13F4)                        0x0304 CMS                            Publishing                     8ztg Medium   Got List Item Version, but item was null. 
01/10/2012 12:48:56.38  w3wp.exe (0x13F4)                        0x0304 Windows SharePoint Services    General                        8kh7 High     There is no Web named "/Vacation Request Qual/Forms/AllItems.aspx". 
01/10/2012 12:48:56.38  w3wp.exe (0x13F4)                        0x0304 Windows SharePoint Services    General                        8e2r Medium   Possible mismatch between the reported error with code = 0x81070504 and message: "There is no Web named "/Vacation Request Qual/Forms/AllItems.aspx"." and the returned error with code 0x80070002.

 Using my account to my calendar works fine.

 I have given the service account site collection admin rights and this is still not working. Any help would be great.