Is there a blank value in the Business field in any record in the Header table?

>Hi,
>
>My report had 02 dbf files that I append to my report.
>However, when review the report, my detail display is
>okay but one of the field in the header section using the other dbf file is empty even thought I had checked and confirm that both dbf file
>are not empty.
>
>What happened, how do I solve this issue. Thank you
>
>My function DisplayDate is listed below
>
>@DisplayDate
>Minimum({Header.Business})