Has_many :through doesn't work with .new()?

so thingys is related to middles which is related to users

    @wamp = Thingy.new
    @wamp.wonko = 13
    @wamp.save

  this is the has many relationship in the thingy model.

  has_many :wonko, :through => :middles, :source => :user

i just keep getting a undefined method wonko.

even though when i pull thingys from the database it has no problem
getting the user related to the thingys.. i'm lost.

so thingys is related to middles which is related to users

@wamp = Thingy\.new
@wamp\.wonko = 13
@wamp\.save

this is the has many relationship in the thingy model.

has_many :wonko, :through => :middles, :source => :user

It would be helpful to see the actual code, and real examples (eg
@wamp.wonko= 13 could never ever work) and the actual error/stack
trace

Fred