Redirect in my custom plugin page in Wordpress

[admin]

Case: I have a form in the page which enables users to add certain values in a simple text file. Now I want to redirect to the same page after values have been added successfully.

The read/write code all works great, I even put redirection code but this would display warning that

header information is already sent

.

Headers I tried:

header("Location: some_url_here_in_same_site");
wp_redirect("some_url_here_in_same_site");

My Form code:

if(isset($_POST['txtName'])}

    // form validation code here
    if(successful)
        wp_redirect("some_url_here_in_same_site");

}

PROBLEM:

<ul>
<li>how can we do redirection in wordpress after form submission in our plugin?</li>
<li>

ob_start

wonb't work, so don't suggest me this either</li>
</ul>