Insert new user with form submit ‘init’ hook

I’m posting a form to insert a new user and hooking my function to ‘init’. This code is in my mu-plugins folder.

The user gets inserted fine, but the page is not loaded after wards.

My form action is empty, so the form should post the same page (which i want) However, i just get a blank page (with header and footer) and the title says page cannot be found.

It looks as if there is a problem with the page’s post?

Below is my function code

/*
*   Register a new reminder_service user
*/
function reminder_register(){
    if(@$_POST['reminder_register']){
        $user["user_login"] = $_POST["email"];
        $user["user_pass"] = $_POST["password"];
        $user["user_email"] = $_POST["email"];
        $user["display_name"] = $_POST["name"];
        $user["user_nicename"] = strtolower(str_replace(" ", "-", $_POST["name"]));
        $user["role"] = 'reminder_service';
        $user["user_registered"] = date('Y-m-d H:i:s');
        $user["show_admin_bar_front"] = false;

        $user_id = wp_insert_user($user);
        if(is_int($user_id)){
            echo 'yes';
        }else{
            foreach($user_id->errors as $error){
                foreach($error as $e)
                    echo $e."<br />";
            }
        }
    }
}
add_action('init', 'reminder_register');

This is my form code

<form action="" id="reminder_register_form" method="post">
                        <fieldset class="blue">
                            <span><legend><div class="circle c_1"></div> Your Details</legend></span>
                            <ul class="form floated">
                                <li>
                                    <label for="name">Your Name<span class="required">*</span></label>
                                    <input type="text" name="name" id="name" class="required">
                                </li>
                                <li class="right">
                                    <label for="postcode">Postcode<span class="required">*</span></label>
                                    <input type="text" name="postcode" id="postcode" class="required">
                                </li>
                                <li>
                                    <label for="email">Your Email<span class="required">*</span></label>
                                    <input type="email" name="email" id="email" class="required">
                                </li>
                                <li class="right">
                                    <label for="mobile">Mobile No<span class="required">*</span></label>
                                    <input type="text" name="mobile" id="mobile" class="required">
                                </li>
                                <li>
                                    <label for="password">Password<span class="required">*</span></label>
                                    <input type="password" name="password" id="password" class="required">
                                </li>
                                <li class="right">
                                    <label for="password_confirm">Confirm Password<span class="required">*</span></label>
                                    <input type="password" name="password_confirm" id="password_confirm" class="required">
                                </li>
                                <li>
                                    <label for="terms" class="radio_label">I agree with the Terms of Service, the Privacy Policy and Terms &amp; Conditions of the Good Dealer Scheme Reminder Service</label>
                                    <input type="checkbox" name="terms" id="terms" class="required" value="yes">
                                </li>
                                <li class="right">
                                    <label for="communication" class="radio_label">Please select if you are happy to receive further communication from the Good Dealer Scheme.  </label>
                                    <input type="checkbox" name="communication" id="communication" value="yes">
                                </li>
                            </ul>
                        </fieldset>
                        <div class="submit_button_container">                               
                            <input type="submit" value="Register" name="reminder_register" class="orange">
                            <label><span class="required">*</span> Please complete these fields before clicking the register button</label>
                        </div>
                    </form>

The way i want this to work is to submit the form to the same page, and show appropriate content based on the result of the user insert