Changing heading gives weird result

When I generate a report and change the heading of the report (uselly on the 1st line), I have some fields that are giving me weird result. The value of the field is replace by question mark sign (?).

Here is an example:
I inserted some tesxt on line 1 in the heading. When I hit the "Display Result" in Viewpoint, the report header is displayed normally. But if I submit the job on the iSeries with the command REPORT, instead of the text in the heading I get question marks.

Any idea what could cause this problem?

I tried different combinaisons on the header of the report, but the minute I change or delete the original header designed by the wizard, I get funny results in the header of my report.

Thanks,
JS