Assertion Error, Trying to add .tif to group layer

Question

So I am trying to add a layer to a group, but running into problems most likely because of the file is a .tif. I have tried quite a few different iterations of this and looked at a few solutions but nothing seems to work, any ideas? I have also tried entering a [0] behind the listlayers command

targetGroupLayer = arcpy.mapping.ListLayers(mxd, "15MinMaps", df)
for row in cursor:

       Sel = (row.getValue(field))
       for dirpath, dirnames, filenames in arcpy.da.Walk(r"Z:/IMAGES/MAPS/15_Min_Thematic_Maps",topdown=True, followlinks=True, type="TIF"):
           for filename in filenames:
               if Sel in filename.upper():
                print filename
                fullpath = (dirpath + "/" + filename)
                print fullpath
                Fname = (dirpath[36:] + " " + filename)
                result = arcpy.MakeRasterLayer_management(fullpath, Fname)
                layer = result.getOutput(0)
                arcpy.mapping.AddLayerToGroup(df, targetGroupLayer, layer, "BOTTOM")
               else:
                   pass

I keep on receiving this error.

Traceback (most recent call last): File "C:\Users\sorrell\AppData\Local\ESRI\Desktop10.2\AssemblyCache{DE572FA2-3589-48E1-8D3E-6E2C0CB31129}\NewOMSIUA_addin.py", line 117, in onMouseDownMap arcpy.mapping.AddLayerToGroup(df, targetGroupLayer, layer, "BOTTOM")

File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\utils.py", line 181, in fn_ return fn(*args, **kw)

File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\mapping.py", line 88, in AddLayerToGroup assert isinstance(target_group_layer, Layer) and target_group_layer._arc_object.isGroupLayer

AssertionError

It will add in the layer but will not add the layer into the group. Edit: I just sliced off the .tif at the end of the name just to make sure the .tif was not messing anthing up in the name. It did not work

Answer 1

Ok, I solved it myself. The problem was that it could not read the name of the layer to be added to group.

for dirpath, dirnames, filenames in arcpy.da.Walk(r"Z:/IMAGES/MAPS/15_Min_Thematic_Maps",topdown=True, followlinks=True, type="TIF"):
           for filename in filenames:
               if Sel in filename.upper():
                print filename
                fullpath = (dirpath + "/" + filename)
                print fullpath
                Fname = (dirpath[36:] + " " + filename[:-4])
                mxd = arcpy.mapping.MapDocument("Current")
                df = arcpy.mapping.ListDataFrames(mxd)[0]
                targetGroupLayer = arcpy.mapping.ListLayers(mxd, "15MinMaps", df)[0]
                arcpy.MakeRasterLayer_management(fullpath, Fname)
                arcpy.mapping.AddLayerToGroup(df, targetGroupLayer, arcpy.mapping.Layer(Fname), "BOTTOM")
                arcpy.mapping.RemoveLayer(df, arcpy.mapping.Layer(Fname))
               else:
                   pass