arcpy - ValueError error from lyr.replaceDataSource()?

I'm trying to write a script that allows me to look through map documents and replace each layer's data source in each map document. Everything is working logically I believe, and all my loops are working as they should. The datasets that are referenced exist. Yet, I am getting this error :

Traceback (most recent call last): File "C:\Python27\ArcGIS10.1\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 326, in RunScript exec codeObject in main.dict File "C:\Users\Daimon Nurse\Desktop\DFMPROJECT\Scripts\editmapdocument8.py", line 18, in Lyr.replaceDataSource(workspace_path, workspace_type, dataset_name) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\utils.py", line 181, in fn_ return fn(*args, **kw) File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy_mapping.py", line 680, in replaceDataSource return convertArcObjectToPythonObject(self._arc_object.replaceDataSource(*gp_fixargs((workspace_path, workspace_type, dataset_name, validate), True))) ValueError: Layer: Unexpected error

This is the code I am using:

 import arcpy
import os

PATH2 = r"C:\Users\Daimon Nurse\Desktop\DFMPROJECT"
arcpy.env.workspace = PATH2

arcpy.env.overwriteOutput=True

for file in arcpy.ListFiles("*.mxd"):
    filePath = os.path.join(PATH2,file)
    MapDoc = arcpy.mapping.MapDocument(filePath)
    lyrList = arcpy.mapping.ListLayers(MapDoc)
    i = 1
    for Lyr in lyrList:
        print Lyr 
        workspace_path =  r"C:\Users\Daimon Nurse\Desktop\DFMPROJECT\DFM"

        workspace_type = "FILEGDB_WORKSPACE"
        dataset_name = 'Zone{0}'.format(i)
        print dataset_name
        print workspace_type
        print workspace_path
        print os.path.join (workspace_path, dataset_name)
        Lyr.replaceDataSource(workspace_path, workspace_type, dataset_name)
    i = i + 1

These are the printed results on the first iteration for dataset_name, workspace_type, workspace_path and os.path.join respectively:

Zone1
FILEGDB_WORKSPACE
C:\Users\Daimon Nurse\Desktop\DFMPROJECT\DFM
C:\Users\Daimon Nurse\Desktop\DFMPROJECT\DFM\Zone1

Answer

The problem was I was listing the dataset in the replacedatasource function when I really just needed to list the name of the feature class itself. for example:

for table in arcpy.mapping.ListTableViews(mxd):
    print table.name
    filename1 = table.name
    table.replaceDataSource(PATH, workspacetype, filename1)

    print "REPLACED!"