search userform looking up wrong cell on sheet

hi
i have a search form,my problem is when i enter a new entry eg,b80 and fill in all textboxes and click add all seems to work,when i enter b80 again sub order no
comes back as wrong no,have checked all code and on saving it goes to cell "m",but when i want to update it looks like its reading "i",i could have missed something,but totally confused now
cheers colin