Hi robmason10,
I interpreted your needs differently--that you need a group header to display information even though there are no related details. It sounds like you already have a left join between the table from which you are drawing your grouped data and the table which contains your detail data, but that when the detail data is null the related group disappears, and you don't want it to.
One way to force the group header to appear would be to create a formula to replace your detail field, which creates a default for the null field, e.g.,
If isnull({detail}) then "N/A" else
{detail} = {detail}
If, instead of the default string, you wanted nothing to appear under the group heading, you could then try suppressing the detail section which contains the formula. I think this would work.
Alternatively, there is a report option which allows you to specify that nulls appear with a default value. I've never used this, and I'm not sure how this works if your field is a string.
-LB