MySQLi of MySQL?

[Lucius1992]

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<img src="<?php echo level_img($sql['userid']); ?>">
<br>
<input name="user_answer" type="text" class="field" />
<input name="logo_id" type="hidden" value="1" />
<input name="username" type="hidden" id="username" value="<? echo $_SESSION['username']; ?>" />
<input name="process" type="submit" class="textfield" id="process" value="Antwoord"/>
<input type=button value="Hint!" onClick="window.alert('<? echo level_hint($sql['userid']); ?>')">
</form>

De gehele website is geschreven in MySQLi maar, is hierboven geschreven in PHP op MySQL of MySQLi? En hoe krijg ik het in orde? Want één ding is zeker, hij werkt niet.