Exporting report data to excel error

hello everyone,

i have this error that occurs each time i try to export a report to excel in dynamics ax 2012 r2, i have posted the event log below, please can anyone explain why this could be happening. I will very much appreciate any help i can get.....

****************************************************************************************************Description:

Object Server 01:  An error has occurred in the services framework.  Method: AifMessageInspector::AfterReceiveRequest.  Error: System.ServiceModel.FaultException: Failed to logon to Microsoft Dynamics AX.

  at Microsoft.Dynamics.Ax.Services.AxServiceOperationContext.InitializeSession()

  at Microsoft.Dynamics.Ax.Services.AxServiceOperationContext.InitializeContext()

  at Microsoft.Dynamics.Ax.Services.AxServiceOperationContext.Attach(OperationContext owner)

  at System.ServiceModel.ExtensionCollection`1.InsertItem(Int32 index, IExtension`1 item)

  at System.Collections.Generic.SynchronizedCollection`1.Add(T item)

 at Microsoft.Dynamics.Ax.Services.AifMessageInspector.AfterReceiveRequest(Message& request, IClientChannel channel, InstanceContext instanceContext)