When clicking submit the form redirects to the registration manager PHP

I am attemping to create a PHP login system using MySQLi. However I have created a HTML Form:

<form action="register_manager.php" method="post">
        <p>Please fill all fields!</p>
        <input type="text" name="username" value="<?PHP print $getuser; ?>" maxlength="15" /><br />
        <input type="password" name="password" placeholder="Password" maxlength="15" />
        <input type="password" name="confirmpassword" placeholder="Confirm Password" /><br />
        <input type="text" name="email" placeholder="E-Mail Address" />
        <p style="margin: 0; padding: 0;">
            (Use a vaid a valid E-Mail Address for activation!)
        </p>
        <p>
            <a href="#">Already got an account?</a>
        </p>
        <input type="submit" name="regsubmit" value="Register"/><br />
        <?PHP echo '<p>'.$errormsg.'</p>'; ?>
    </form>

Once I click submit, it redirects me to the registration_manager.php page, which is not what I am wanting it to do. I am new to PHP so I am not aware on why it is doing this, instead of registering the user.

This is the register_manager.php file: http://ift.tt/1EY2vI6

If you could help me, that would be great.

Thanks in advance