             @fired = 1
             @complete error
             @results = [null, error]
+            undefined
 
         # call progress to provide updates on the progress on the completion of the promise
         progress: (update) -> 

            if progressCallback == mutator 
                returnDeferred = this
            else 
                returnDeferred = new clazzy.Deferred()
                returnDeferred.canceller = @cancel
            listener = 
                resolved: resolvedCallback,

                progress = listener.progress
                progress and progress update
                listener = listener.next
            undefined
        addCallbacks: (callback, errback) ->
            @then callback, errback, mutator
            this
