Conditional formatting with blank string

[Brian]

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?

[Brian]

Figured it out.  Instead of the wizard, I edited the properties directly and that fixed it.