echo htmlentities($var) doesn't work

Question

I get a string from the database, and i want to output that string with the function htmlentities or htmlspecialchars.

The problem is that when I echo the variable without htmlentities, it outputs the string just like it should, but when I echo the variable WITH htmlentities, it outputs nothing.

Code:

This works:

<h2><?php echo $row['title']; ?></h2>
<p><?php echo $row['description']; ?></p>

This doesn't work:

<h2><?php echo htmlentities($row['title']); ?></h2>
<p><?php echo htmlentities($row['description'], ENT_COMPAT, "UTF-8"); ?></p>