can't program a PIC using PICPROG (linux) for the second time (after first burning)

I can't program a PIC using picprog in linux after first successful burning. I mean it is showing following error.
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vinod@ubuntu:~/pic$ sudo picprog --erase --burn --slow --input-hexfile=877.hex --reboot
[sudo] password for vinod:
Picprog version 1.9.1, Copyright © 2010 Jaakko Hyvätti <Jaakko.Hyvatti@iki.fi>
Picprog comes with ABSOLUTELY NO WARRANTY; for details
type `picprog --warranty'. This is free software,
and you are welcome to redistribute it under certain conditions;
type `picprog --copying' for details.

Trying realtime priority 1
Bound to CPU 0
Power off.
Using 10 µs delays.
/dev/ttyS0: id 0x0e28: detected pic16f877a version 0x08
Device pic16f877a, program memory: 8192, data memory: 256.
Erased and removed code protection.
Burning program memory,/dev/ttyS0:00a5: programmed=3027, read=3003:unable to verify pic while programming.
Is code protection enabled, or does the chip need to be
erased completely before programming?
Use --erase option to disable code protection.
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i think that u are enabling write protection try after disable them with a new ic