arcpy - Insert layer file to specific data frame

I have a folder that contain mxd's projects. Each mxd has 3 and more data frame. I want to insert layer file to a specific data frame with position in the TOC. I don't know how to do it. I'm trying this code:

import arcpy,os,sys
import arcpy.mapping
from arcpy import env




env.workspace = r"C:\Projects"   
for mxdname in arcpy.ListFiles("*.mxd"):
    print mxdname
    mxd = arcpy.mapping.MapDocument(r"C:\Projects\\" + mxdname)
    insertLayer = arcpy.mapping.Layer(r"C:\Projects\layers\ways.lyr")
    dfList = arcpy.mapping.ListDataFrames(mxd, "*")
    for df in dfList:
        for lyr in arcpy.mapping.ListLayers(mxd, "", df):
            if lyr.name =="residence":

                arcpy.mapping.InsertLayer(df, lyr, insertLayer, "AFTER") 
                print 'InsertLayer'          
    mxd.save()
del mxd

Answer

That code are worked:

import arcpy,os,sys
from arcpy import env

env.workspace = r"C:\Project"   

for mxdname in arcpy.ListFiles("*.mxd"):
    print mxdname 
    mxd = arcpy.mapping.MapDocument(r"C:\Project\\" + mxdname)
    df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]                                       
    LayerList = arcpy.mapping.ListLayers(mxd, "abc", df)
    if len( LayerList) == 0:
        continue
    insertLayer = arcpy.mapping.Layer(r"C:\Project\layers\ways.lyr")
    arcpy.mapping.InsertLayer(df,  LayerList [0], insertLayer, "AFTER")
    print 'InsertLayer'

    mxd.save()
del mxd