Problem doing a joins in signups

gistfile1.txt

# Problem: doing a .joins(:user) when using mySQL returns an empty array even when signups exist. The reason I am doing a joins is so that I can sort by user name.

### works in SQLlite  ###

>>> o.signups.joins(:user).order('users.first_name ASC')
  Signup Load (1.3ms)  SELECT "signups".* FROM "signups" INNER JOIN "users" ON "users"."id" = "signups"."user_id" WHERE "signups"."occurrence_id" = 8 ORDER BY users.first_name ASC

 => [#<Signups ...>] 


>>> o.signups
 Signup Load (1.9ms)  SELECT "signups".* FROM "signups" WHERE "signups"."occurrence_id" = 8

=> [#<Signups ...>] 


### Doesn't work in mySQL ###

>>> o.signups.joins(:user).order('users.first_name ASC')
  Signup Load (1.7ms)  SELECT `signups`.* FROM `signups` INNER JOIN `users` ON `users`.`id` = `signups`.`user_id` WHERE `signups`.`occurrence_id` = 8 ORDER BY users.first_name ASC

 => []   ### returning empty array, even when i do just .joins(:user) and leave out the order part

>>> o.signups
  Signup Load (0.7ms)  SELECT `signups`.* FROM `signups` WHERE `signups`.`occurrence_id` = 8

 => [#<Signups ...>]