hi Clifton,
if you've already gone into the report options and chosen to convert the nulls, then try something like this for the grouping formula...
if
{MyTable1.Field1} >= 'a'
then
{MyTable1.Field1}
else
{MyTable6.Field3}
there could be other characters in there other than chr(32)...trim() deals with chr(32).
-jw