I want to make a Group Header invisible when the group field is blank. In the conditional formatting tool, I selected the correct field, the expression is "=" and I select <blank> for the value in the dropdown list. I then unchecked the Layout/Visible field. When the report runs though, the header continues to show even when the field is blank (e.g. =''). I've tested it with a known value and it does make the header invisible so it seems that it's not detecting the blank value correctly. What am I doing wrong here?