Hi,
Same error occurs.
I've tried to recreate the append structure.
Append structure per table.
BKPF ZNEWFIELDS_FB601
VBKPF ZNEWFIELDS_FB602
BSEG ZNEWFIELDS_FB603
Then I created a new custom program in SE38(ZFB60_UPDATE).
Copied the code in the site and paste it inside the custom program.
Then I create a screen in SE80 and enter the code.