Custom Error Handler

I am a novice at programming but have been successful at writing some python code. I am trying to write a custom error handler and have the error msg displayed in the in tool's process dialog box. Message will print in python shell but not in process dialog box when run from a tool.

# import the required modules for the python script
import arcpy, os, sys, traceback

class NoCaseFld(Exception):
pass

# define common variables here

caseFlds = "lU_CURRENT;TRACT"
caseOrder = "tract lucurrent"
orderErr = ""
fldFound = 1


try:

# 1. If case field(s) selected, check for a specified sort order and create list object
if caseFlds != "":
if caseOrder != "":
orderUpper = caseOrder.upper()
if " " in orderUpper:
orderList = orderUpper.split(" ")
elif "," in orderUpper:
orderList = orderUpper.split(",")
elif ";" in orderUpper:
orderList = orderUpper.split(";")
else:
fldFound = -1
orderErr = caseOrder #error in reading case field order


# i. Verify sort order list values are found in case field(s) list
caseUpper = caseFlds.upper()
for f in orderList:
for c in caseUpper.split(";"):
if c == f:
fldFound = 1
continue
else:
fldFound = -1

if fldFound == -1:
orderErr = orderErr + f


if fldFound == -1:
raise NoCaseFld

except NoCaseFld:
print "Error: Case Field Name Order\nfield name(s) not found in table:\n" + orderErr



except: #error handeling code

tb = sys.exc_info()[2]
tbinfo = traceback.format_tb(tb)[0]
pymsg = "PYTHON ERRORS:\nTraceback Info:\n" + tbinfo + "\nError Info:\n " + str(sys.exc_type) + ": " + str(sys.exc_value) + "\n"
msgs = "ARCPY ERRORS:\n" + arcpy.GetMessages(2) + "\n"

arcpy.AddError(msgs)
arcpy.AddError(pymsg)

print msgs
print pymsg

arcpy.AddMessage(arcpy.GetMessages(1))
print arcpy.GetMessages(1)