Unchecked Mandatory for some items in Join page from admin panel as optional items for Join Page,

but they remain mandatory items resulting to failure to join in. Same issue for D7 B2.

If you have not removed minimum value in the fields you no longer want mandatory you will get a error stating that field needs to contain a minimum of X characters.

Remove the minimum values, Give that a try.

Ticket #910

http://www.boonex.com/trac/dolphin/ticket/910