Assign Z value from DEM to line ends

PLEASE HELP URGENT - Is there anyone at all who can help with this? I wrote a script based on the Extract Value To Points tool but it doesn't work properly.

I have a simplified line shapefile and I want to add elevation (z values) from a DEM raster layer to the end points of the lines.

I have written the following code (its user input) but when I run it as a tool it reports that it has run successfully but it doesn't actually output the point shape file with the z values!

Any hints or even alternative suggestions would be appreciated.

code -

# script to extract raster values to point shapefile
# adapted by Scott MacDonald Kingston University k0848626 GSM655Programming Asssignment C

# import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# get user supplied path, layers and fields
path = arcpy.GetParameterAsText(0)
arcpy.env.workspace = path

# in Feature Layer is Confluence_Pts
in_point_features = arcpy.GetParameterAsText(1)
# in Raster Layer is DEM
in_raster = arcpy.GetParameterAsText(2)
# out Feature Class
out_point_features = arcpy.GetParameterAsText(3)

# error trapping measures
try:
# check out spatial analyst extension
arcpy.CheckOutExtension("Spatial")

# run the ExractValuesToPoints tool
arcpy.ExtractValuesToPoints(in_point_features, in_raster, out_point_features)

# check in spatial analyst extension
arcpy.CheckInExtension("Spatial")

except:
print arcpy.GetMessages()