In reports dictionary step 4, the form displays 2 radioboxes for "All dates" and for "Date range". If "All dates" is set, the definition saves with an empty condition. (With and without patch, see dictionary.pl line 152.) To have a condition saved, "Date range" and at least one of the dates "Start of date range" and/or "End of date range" has to be set. Conclusion: The checkboxes could be removed. This needs some changes in dictionary.pl line 152 and following. See Bug 2669, comment #4