Mail sending failed

In my form i have a stock detail field if any of the item is less than <20 then mail goes to that person that is listed in the dialog list . but that dialog list is present in the first subform .mail did not goes .

but when i create a field in that requester form it will work .

i use simple

MailDoc.CopyTo=doc.fieldname(0)

can its possible that i can send mail without selecting people from dialog list . and that list is present in any subforms .

if anyone have any idea plz suggest me…