You will get this error, if you are combining and bringing data into a single block from 2 or more DP’s.
Follow this link, on how to resolve it, Link is from Reporter FAQs:
https://bobj-board.org/t/15226/2
In my opinion, you should build the block from scratch, then you can rename your column headings.
Good Luck.
BO_Chief 
(BOB member since 2004-06-06)