18F458 programming problem

Hi, I use wisp628 & xwisp soft to program 18F458 but this happens:

C:\Program Files\XWisp>xwisp.py target 18F458 go rs232.hex
XWisp 1.06, command line mode
>>> COM1
C:\Program Files\XWisp\serialwin32.py:88: DeprecationWarning: integer argument e
xpected, got float
win32file.SetCommTimeouts(self.hComPort, timeouts)
hardware: Wisp628 1.09 (fast)
C:\Program Files\XWisp\xwisp.py:1540: FutureWarning: %u/%o/%x/%X of negative int
will return a signed string in Python 2.4 and up
self.Log(( "__GoTo( %04X )" % Address ) + \
target confirmed: 18f458, revision 04
read Fuses 300000Traceback (most recent call last):
File "C:\Program Files\XWisp\xwisp.py", line 2730, in ?
XWisp_Main()
File "C:\Program Files\XWisp\xwisp.py", line 2727, in XWisp_Main
Wisp_Line().Interpret()
File "C:\Program Files\XWisp\xwisp.py", line 2347, in Interpret
self.Execute( Command )
File "C:\Program Files\XWisp\xwisp.py", line 2329, in Execute
exec( 'self.CMD_' + Command.upper() + '()' )
File "<string>", line 1, in ?
File "C:\Program Files\XWisp\xwisp.py", line 1826, in CMD_GO
self.Bus_Target.Write_Verify( self.Patched_Image())
File "C:\Program Files\XWisp\xwisp.py", line 1691, in Write_Verify
raise IOError, 'verification failure: ' + Diff
IOError: verification failure: different data at address 300000: file=FF target=00

there is always difference in fuse addresses 0x300000 - , that is wrong?
Thanks.