Problem in IAP

 Problem in IAP

Hello!

I am using LPC2138, and want to write data into the ROM during program execution.I found a help code at
http://www.keil.com/download/docs/298.asp?bhcp=1

the code is compiled and loaded into the controller successfully.

The problem is when to write or erase,
when a sector is prepared for write/erase the command executes successfully but when the second cammand i.e write RAM to Flash, the error code 9 is returned, which means corresponding sector is not prepared for writing/erasing.

Can not understand the problem. No changes have been done in the IAP.C

Thank you in advance
Looking for Response