pass value from child form to parent

I am trying to pass the value form a child form that was called from a parent form and having diffulty.

The child form is set like this

<form name="frmReq" onSubmit="passVals()" >

</form]

Code (markup):

In the head the child form html doc I have

<script>
function passVals() {

   document.appts.req_f_name.value ='testing';
   //appts is the name of the parent form
  //req.f_name is the name of a text box on the parent form


}
</script>

Code (markup):

I would like to know what I am missing or any ideas?

THanks

 

Ok I got it I have to add .document

window.opener.document.appts.req_f_name.value ='testing';