Adding Feedburner Email Subscription Box via PHP

I am trying to add feedburner email subscription box via shortcode. But it gives a php error. How can i add that??

function get_newsblock($atts) {
return 'Subscribe to the Free eBooks Daily Email Newsletter, Enter your Mail id below;
<div class="email-box"><form action="http://feedburner.google.com/fb/a/mailverify" method="post" onsubmit="window.open('http://feedburner.google.com/fb/a/mailverify?uri=example', 'popupwindow', 'scrollbars=yes,width=550,height=520');return true" target="popupwindow"><input id="email" class="email" style="width: 150px; font-size: 12px;" onfocus="if(this.value==this.defaultValue)this.value='';" onblur="if(this.value=='')this.value=this.defaultValue;" type="text" name="email" value="Enter Your Email" /> <input type="hidden" name="uri" value="example" /> <input type="hidden" name="loc" value="en_US" /> <input class="subscribe" type="submit" name="commit" value="Subscribe" /></form></div>';
}
add_shortcode('newsblock', 'get_newsblock');