提交后，页面不会重定向（返回）到Facebook App中的主页面

I've a facebook App where a form is pull from my website. After submit the form in facebook it's showing success message. But In my process.php page i set header code to re-direct to my main facebbok page after showing success message. But it's not rejecting. Do you know why ? and is there any solution ?

echo "<div class='success'><font color='green' size='5'>Congratulation!. Successfully submited your 
recipe. Thank You.</font/></center></div>";
header("Refresh:5; url=myfbmainpage.php");

Try following:

header("Refresh: 5;");
header("Location: myfbmainpage.php");