I created a file called "page.php" with the below code.

```
<!DOCTYPE  HTML>
<html>
    <body>
        <?php
            require 'form.php';
        ?>
        <a href="#" onclick="call_popup('form_container')">Click this link!</a>
   </body>
</html>

```

And I created another file "form.php" with the below code:

```
<script type="text/javascript">
    function call_popup (container_id) {
        var id= document.getElementById(container_id);
        alert(id);
    }
</script>
<div id="form_container">
    <form>
        <input type="text" />
        <input type="button" value="submit" />
    </form>
</div>

```

I am trying to call the "call\_popup(container\_id)" function in "page.php" which is defined in "form.php". When I click the "Click this link!" of the anchor tag it gives an error saying `call_popup('form_container')` not found!

Where did I go wrong?