Emoji's Displaying as Plain Text
After upgrading to Mavericks, whenever I type out a smiley (screenshot: http://cl.ly/image/210a430a2d2k) it displays as normal, plain text and not as a smiley icon. If I select an emoticon from teh drop down menu, though, it works. But it does not automatically translate symbols into emoji as it previously did. How can I fix this? Thank you!
iMac (24-inch Early 2008), Mac OS X (10.7.3)