when you call the dialog first from the menu (share...), this button is grayed out. Do "paying member" mean PGC-paying members?
Did you put in a valid! profile name into the field above the button (you should get response from the selector)?
Does the profile name, you tried with, have special characters or signs?
If nothing helps, remove all of the share profiles and add them all at once again.
...otherwise I've not seen such behaviour and no further idea and it would be a good idea to check with the site owner here.