Diagnosis
On the initial screen, you chose function Goto --> Headeroverview. However, the BOM only has one header with the validityarea or cutoff date entered.
One header only is valid on the cutoff date.
Only one header exists within a validity area, unless the header waschanged with history in the given interval.

Procedure
Choose function Header full to edit or display the BOM header.
In display mode, you can display the BOM over the whole validity areaby deleting the valid from date on the initial screen. To do this,enter "!" at the beginning of the field Valid from and choosefunction Goto --> Header overview again.