popup validation message

i have tried using the following

add_filter( 'gform_validation_message', 'sw_gf_validation_message', 10, 2 );

function sw_gf_validation_message( $validation_message ) {

	//display error JS popup
	add_action( 'wp_footer', 'sw_gf_js_error' );

}

function sw_gf_js_error() {
	?>
	<script type="text/javascript">
		alert( "Please fill out all required fields indicated by a *" );
	</script>
	<?php
}

but it didnt get me anywhere, any ideas?
http://www.targanpender.com/