Because the wizard is limited.
You can have a maximum of 255 fields on a report (unless you resort to using
a subreport)
You can have a maximum of 754 controls on a report.
You can start building the report with the wizard and a limited number of
fields. Then once the report is built by the wizard, you can add the
remaining controls and fields.
--
John Spencer
Access MVP 2002-2005, 2007-2008
Center for Health Program Development and Management
University of Maryland Baltimore County
..