jQuery Grid Plugin - jqGrid

Im trying to edit Sub grid – first row is editing all right but in the second (and more) I’m getting error:

obj.p.colModel[i] is undefined
nm = obj.p.colModel[i].name.replace(’.',”\\\\.”);;

file: grid.formedit.js

i understand it’s because there is no such obj.p.colModel for [i] but why each function sees non existing [i] ?

Another question - why at the end of the line are 2 ;; ?