Using Civi linked to joomla web to manage our membership and various mailing lists.
I would like to be able to use a custom search function to find, for example, individuals who are not members, or individuals who are not in our 'newsletter' contact group. Contacts who are not in a give contact group.
I imagine the Custom Search Include/Exclude function would be best for this but when I select this from the Custom Search List I get an error message 'At least one Group and Tag must be present for Custom Group / Tag search.'
Can anyone advise what this means and how I might conduct such a search?