Custom field not showing on Functional Object

Hi, 

We have created a custom tab on the Functional Object screen with several custom fields.  I am trying to add another custom field to the custom tab, but I can’t get the field to show.  I’ve added the field.  It’s approved, pulbished and synchronized and I’ve reloaded the configuration but when I go to the Object Properties, it’s not in the list for me to add to the tab.  What am I missing?