Navicat 8 for MySQL and PHP?

[CSGames]

I made a database in the localhost part of Navicat 8 for MySQL called testu.
i put an sql file in there but thats not the problem...
in a php file i put:

<?php
// Connecting, selecting database
$link = mysql_connect('localhost')
    or die('Could not connect: ' . mysql_error());
echo 'Connected successfully<br>';
mysql_select_db('testu') or die('Could not select database<br>');

// Performing SQL query
$query = 'SELECT * FROM username';
$result = mysql_query($query) or die('Query failed: ' . mysql_error() . "<br>");

// Printing results in HTML
echo "<table>\n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
    echo "\t<tr>\n";
    foreach ($line as $col_value) {
        echo "\t\t<td>$col_value</td>\n";
    }
    echo "\t</tr>\n";
}
echo "</table>\n";

// Free resultset
mysql_free_result($result);

// Closing connection
mysql_close($link);
?>

I downloaded wamp. I type in the address bar: localhost/phpfilename.php

and what appered was:
Connected successfully
Could not select database

what is the problem?
i put the correct name for the database..