Error in AIF Webservice in Ax2012

Hi All,

         During Activating or Deactivating a particular webservice created earlier under the inbound port in System Administration-->Setup-->Services & AIF--> in bound port, i am getting the following error

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"System.OperationCanceledException: AIF service group not activated.  Service group: Productcreation.  Error: The specified service type 'Microsoft.Dynamics.Ax.Services.Productcreation' could not be found in the service assembly. ---> System.ArgumentNullException: The specified service type 'Microsoft.Dynamics.Ax.Services.Productcreation' could not be found in the service assembly.

   at Microsoft.Dynamics.Ax.Services.AifHelper.PublishServices(String serviceGroupName)

   --- End of inner exception stack trace ---

   at Microsoft.Dynamics.Ax.Services.AifHelper.PublishServices(String serviceGroupName)

   at Microsoft.Dynamics.Ax.Services.AifHelper.PublishAllServiceGroups(Dictionary`2 faultedServices)"

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and because of it the webservice is not running,.

                                                                                   so can any one please elaborate how this issue can be resolved.

Thanks & Regards

Rajveer.