Debugging error 000865 in Python script tool for use with raster elevations?

I'm trying to create a python script tool that will take in a DEM/raster as a parameter, pull out the maximum and minimum elevation values, and iterate through this range of values at a specified counting interval.

This script outputs the resulting raster masks to an output geodatabase, as another parameter. I keep getting the error '000865: Input Raster: inDEM does not exist' when I try to run my script tool. I'd like help resolving this issue in my code, as I'm not sure what the cause is.

import arcpy
from arcpy.sa import *
import os

arcpy.CheckOutExtension("Spatial")
arcpy.env.overwriteOutput = True


inDEM = arcpy.GetParameterAsText(0)
intervalElevation = int(arcpy.GetParameterAsText(1))
outGDB = arcpy.GetParameterAsText(2)

elevMinResult = arcpy.GetRasterProperties_management("inDEM", "MINIMUM")
elevMaxResult = arcpy.GetRasterProperties_management("inDEM", "MAXIMUM")

minElevation = elevMinResult.getOutput(0)
maxElevation = elevMaxResult.getOutput(0)

myElevations = range(minElevation, maxElevation, intervalElevation)

for elev in myElevations:

    outDEM = os.path.join(outGDB, "lessthan" + str(elev))
    outLessThan = LessThan(inDEM, elev)
    outLessThan.save(outDEM)
    print "Finished " + outDEM