Google plus error upon activation

When attempting to turn on the google plus plugin, I get the following fatal error:

Fatal error: Cannot redeclare class URI_Template_Parser in /home/itnstv/public_html/gethealthyjamaica.com/wp-content/plugins/wpmu-dev-plusone/lib/external/google/external/URITemplateParser.php on line 30

I am not sure as to why this would happen. Any help is greatly appreciated.

Thanks