Revcms referral system

[Thatboysab]

Hey guys! I set up the revcms referall system jardenc created. Everything works fine till a user registers and adds a name to the referral input box. When they click submit, it takes them to a white screen... meaning the php code is fucked up. Butt...... i cant seem to find the problem.

This is whats in my class users:

     final public function ref($post){
        if(!$this->nameTaken($post)){
        echo'The user you referred does not exist';
        }else{
                 global $engine;
        $this->addUser($template->form->reg_username, $core->hashed($template->form->reg_password), $template->form->reg_email, $_CONFIG['hotel']['motto'], $_CONFIG['hotel']['credits'], $_CONFIG['hotel']['pixels'], 1, $template->form->reg_figure, $template->form->reg_gender, $core->hashed($template->form->reg_key));
        $engine->query("UPDATE users SET seasonal_currency=(`seasonal_currency`+1) WHERE username='".$post."'");
        $engine->query("UPDATE users SET ref=(`ref`+1) WHERE username='".$post."'");
        }
        }

This is my register.php ( I changed it up a bit to see if it will work, but it didn't)

<div class="form-group">
<label for="email-address">Referrer (Optional)</label>
<input tabindex="5" type="text" id="email" size="35" maxlength="48" value="" name="ref" class="form-control input-lg" placeholder="referral" autofocus="">
</div>

What is the problem here?

[MentaL]