Make Route with Python and Network Analyst in ArcGIS Desktop giving ERROR 000192

Question

I'm having trouble debugging my python code to create a network analyst layer in ArcGIS 10.0. Basically when run from a script tool the code completes successfully without actually doing anything or returning any sort of useful information, and when run from the embedded python window in ArcGIS 10.0 i get the following error.

"Runtime error <class 'arcgisscripting.ExecuteError'>: Failed to execute. Parameters are not valid. ERROR 000192: Invalid value for Time Attribute Failed to execute (MakeVehicleRoutingProblemLayer)."

The script is supposed to solve the route and create a layer file for the output Here is my code below:

#Import system modules
import arcpy
from arcpy import env
try:
 #Check out the Network Analyst extension license
 arcpy.CheckOutExtension("Network")
 #Set environment settings
 env.workspace = r'C:\Layout3.gdb'
 env.overwriteOutput = True
 #Set local variables
 inNetworkDataset = r'C:\Layout3.gdb\NtsFDS\NtsFDS_ND'
 outNALayerName = "TestResult"
 
 impedanceAttribute = "CABLE_COST"
 distanceAttribute = "TRAVEL_TIME"
 timeUntis = "Minutes"
 distanceUntis = "Meters"
 inOrders = r'\Layout3.gdb\NtsFDS\Orders'
 inDepots = r'C:\Layout3.gdb\NtsFDS\Depots'
 inRoutes = r'C:\Layout3.gdb\NtsFDS\Route'
 outLayerFile = env.workspace + outNALayerName + ".lyr"
 
 outNALayer = arcpy.na.MakeVehicleRoutingProblemLayer(inNetworkDataset, outNALayerName,
 impedanceAttribute,
 distanceAttribute)
 
 outNALayer = outNALayer.getOutput(0)
 
 subLayerNames = arcpy.na.GetNAClassNames(outNALayer)
 
 ordersLayerName = subLayerNames["Orders"]
 depotsLayerName = subLayerNames["Depots"]
 routesLayerName = subLayerNames["Routes"]
 
 candidateFields = arcpy.ListFields(inOrders)
 orderFieldMappings = arcpy.na.NAClassFieldMappings(outNALayer, ordersLayerName,
 False, candidateFields)
 arcpy.na.AddLocations(outNALayer, ordersLayerName, inOrders, orderFieldMappings,"")
 
 depotFieldMappings = arcpy.na.NAClassFieldMappings(outNALayer, depotsLayerName)
 arcpy.na.AddLocations(outNALayer, depotsLayerName, inDepots, depotFieldMappings, "")
 
 arcpy.na.AddLocations(outNALayer, routesLayerName, inRoutes, "", "")
 
 #Solve the VRP layer
 arcpy.na.Solve(outNALayer)
 
 #Save the solved VRP layer as a layer file on disk with relative paths
 arcpy.management.SaveToLayerFile(outNALayer,outLayerFile,"RELATIVE")
 
 print "Script completed successfully"
except Exception as e:
 # If an error occurred, print line number and error message
 import traceback, sys
 tb = sys.exc_info()[2]
 print "An error occured on line %i" % tb.tb_lineno
 print str(e)

Answer 1

For this code to run you will need to upgrade to ArcGIS Desktop 10.1 because the ArcPy Network Analyst module (arcpy.na) was only introduced at that release - see What's new for geoprocessing in ArcGIS 10.1.