Call Parent Window Function From Child Window?

I have created and opened a child window called "checkwin" and have written some data to it. If the data is valid, I want the user to click on the 'CONFIRM' button on the child window, at which time I want the "submit()" function for the form on the parent window to be executed. If the data is invalid the user clicks on 'MODIFY' and I want focus to return to a field on the parent form. However, when I click on the "CONFIRM" or "MODIFY" buttons on the child window, nothing happens. Here is the code:

checkwin.document.write("</td></tr><tr><td align='right'><input type='button' value='CONFIRM'
onclick='opener.document.personnel_form.submit()'></td><td></td><td><input type='button' value='MODIFY'
onclick='opener.document.personnel_form.first_name.focus()'></td></tr></table>")