Arcpy Network Analyst solver error

Hello GIS Stack Exchange,

I am finding it difficult to load locations to sublayers using python in ArcGIS 10.0 network analyst Vehicle routing problem.

I’m also having some trouble debugging my code. Basically i keep getting the following error from the Solve_na function

“An error occured on line 72
ERROR 030092: VRP Solver failed due to invalid input.
Invalid input in the NA classes.
Failed to execute (Solve).”

It strikes me that even though there is an error, the depot and orders network analyst sublayers are well loaded with values from the input feature classes, while the routes network analyst sublayer does not load the values from its corresponding feature class. This implies that there must be a problem adding locations to the route from the corresponding route feature class that i created.

Here is the code below

import arcpy
from arcpy import env

try:
    arcpy.CheckOutExtension("Network")

    env.workspace = arcpy.GetParameterAsText(0)
    env.overwriteOutput = True

    inNetworkDataset = arcpy.GetParameterAsText(1)
    outNALayer = arcpy.GetParameterAsText(2)

    impedanceAttribute = "CABLE_COST"
    distanceAttribute = "Cable_Length"
    timeUntis = "Minutes"
    distanceUnits = arcpy.GetParameterAsText(3)
    inTurbines = arcpy.GetParameterAsText(4)
    inDepots = arcpy.GetParameterAsText(5)
    inRoutes = arcpy.GetParameterAsText(6)

    depotFieldMappings = "Name Name #;"
    routeFieldMappings = "Name Name #; StartDepotName StartDepotName #; EndDepotName EndDepotName #; StartDepotServiceTime StartDepotServiceTime #; EndDepotServiceTime EndDepotServiceTime #; EarliestStartTime EarliestStartTime #; LatestStartTime LatestStartTime #; Capacities Capacities #; FixedCost FixedCost #; CostPerUnitTime CostPerUnitTime #; CostPerUnitDistance CostPerUnitDistance #; OvertimeStartTime OvertimeStartTime #; CostPerUnitOvertime CostPerUnitOvertime #; MaxOrderCount MaxOrderCount #; MaxTotalTime MaxTotalTime #; MaxTotalTravelTime MaxTotalTravelTime #; MaxTotalDistance MaxTotalDistance #; SpecialtyNames SpecialtyNames #; AssignmentRule AssignmentRule #;"
    turbineFieldMappings = "Name NAME #; TimeWindowStart1 TimeWindowStart1 #; TimeWindowEnd1 TimeWindowEnd1 #; MaxViolationTime1 # 0"

    outLayerFile = "C:/data/output" + "/" + outNALayer + ".lyr"

    arcpy.MakeVehicleRoutingProblemLayer_na(inNetworkDataset,outNALayer,
                                            timeUntis,distanceAttribute,
                                            "Minutes", distanceUnits, "1/1/1900", "#", "Low","#",
                                            "NO_UTURNS", "#", "TRUE","","STRAIGHT_LINES")

    arcpy.AddLocations_na(outNALayer, "Depots", inDepots, depotFieldMappings,"")

    arcpy.AddLocations_na(outNALayer, "Routes", inRoutes, , "")

    arcpy.AddLocations_na(outNALayer, "Orders", inTurbines, turbineFieldMappings,"")  

    arcpy.Solve_na(outNALayer)

    arcpy.SaveToLayerFile_management(outNALayer,outLayerFile,"RELATIVE")

    arcpy.AddMessage("Script completed successfully")

except Exception as e:

    import traceback, sys
    tb = sys.exc_info()[2]
    arcpy.AddMessage("An error occured on line %i" % tb.tb_lineno)
    arcpy.AddMessage(str(e))