2 main things to look for. One is your joins. If you are joining two (or more) tables you may need to use a left outer join to get all the records from the one table that has the field you are grouping on. If there are no matching records in the other table(s) these would be excluded from your report by the inner join.
The other thing is your select statement. Make sure it is written in such a way as to to include items that have "none". Also be aware that your select statement may make your outer join into an inner joing by excluding records.
Either of these circumstances will prevent the group from appearing with no details.
Does this solve your problem?