prototype - Rails not submitting form values -

working on old app uses rails/prototype view helpers/rjs extensively. have recurring problem (happens half dozen times week, on same pages) form params not getting submitted. controllers point of view, params hash contains values router able pick route. looking @ forms themselves, tend basic.

one thing in common use remote_form_for, has form disabling code runs after prototype kicks off ajax. in few places, more explicit, (uses ancient syntax, started rails 1 app):

remote_form_for :pallet_move,    :row_id => 'new_pallet_move',    :html => {:id => 'new_pallet_move_form'},    :method => :post,    :after => "$('new_pallet_move_form').disable();',   :url => create_many_pallet_moves_path |f| 

in controller, doing this

palletmove.new params[:pallet_move].merge(:move => move) 

now, code works like, 99% of time. according hoptoad, ten times in last month, nomethoderror: undefined method 'merge' nil:nilclass params {"move_id"=>"908097", "action"=>"create_many", "controller"=>"pallet_moves"}

just sort of looking see if people have seen before, or have ideas investigation, cause sort of out of ideas.