if (! $date_to_use) {
    $msg =  "Enter or confirm the date to schedule. \n";
    while (! $date_to_use) {
        $msg .= "  (mmmdd, mmmd, or mmm dd)\.\n";
        $intext = $excel->InputBox("$msg","Enter date","$assumed_date");
        go_away(16,"Quitting as requested\.") if ($intext eq "0");
        $date_to_use = check_date($intext);
        $msg = "Date error.  Re-enter.\n" if (! $date_to_use);
    }
}