the error is caused by the blank line at line 5.
change lines 4 - 6:
<?php require_once("../../webassist/form_validations/wavt_validatedform_php.php"); ?>
<?php
to:
<?php require_once("../../webassist/form_validations/wavt_validatedform_php.php"); ?>
<?php
for more details on troubleshooting the headers already sent error, see the following post:
showthread.php?t=19285