RasterToPolygon tool is looking inside the output location and not reading the fields

Question

I am trying to convert IMG classified rasters to polygons. I created a code using the Raster to Polygon tool and it worked for 8 of the 50 files; for the rest, I get errors 010157 (Unable to open feature class C:Data\NewLayers\ClassifiedRaster. Failed to execute (RasterToPolygon).) and 010010 (Field not found. Invalid field index obtained. Failed to execute (RasterToPolygon)). What is weird about the first error is that the folder NewLayers is actually the output folder and the workspace is set to C:Data so I don't understand why it is looking for the input file in the output folder. The weird thing about the second error is that field does exist in every raster that the error occurs in. Does anyone have any suggestions? Here is my code:

arcpy.env.workspace = r"C:Data"
arcpy.env.overwriteOutput = True
listras = arcpy.ListRasters("*", "IMG")
for ras in listras:
    name = ras.split(".")[0]
    outws = r"C:Data\NewLayer"
    outras = outws + "\\" + name + ".shp"
    try:
        try:
            arcpy.RasterToPolygon_conversion(ras, outras, "NO_SIMPLIFY","Class_Name")
        except:
            arcpy.RasterToPolygon_conversion(ras, outras, "NO_SIMPLIFY","Class_Names")  
    except:
        #If the field does not exist, then list the fields so I can see what it might be called.
        #So far each raster that comes into the Except prints a field called Class_Name or Class_Names
        flist = arcpy.ListFields(ras)
        whatfields = []
        for f in flist:
            whatfields = f.name
            print str(name) + ": " + str(whatfields)