With the latest update of W3 Total Cache, it broke the mobile detection (probably page caching issues).
I found a great post of how to fix it written by the author of this plugin: http://websitez.com/how-to-get-w3-total-cache-mobile-plugins-to-work/
However, their link is broken to the function that needs to be changed in W3 Total Cache: http://snipplr.com/view/70071/wp-mobile-detector--0928/
Anyone know what the snippet is that replaces group_verifier()? Or can the Author of this plugin provide the snippet?