I Used Writecode for pic18F877 and it work OK, but when I used it for Pic18F458 it is not OK. It is not OK for pic18F4580 too.

Please Check this code for pic18f458

W var word
W=$1234
writecode $200,W
writecode $300,W

stop

end

I can check Flash in pic18f458 after writing process in EPIC PROGRAMMER (withaut LCD ..)