I set up LogEntry for use with Mediawiki 1.26. When I add <logentry /> to the page after installing the plugin in Mediawiki 1.26, I now see the following (instead of a log entry box):
UNIQ--logentry-00000001-QINU
LogEntry Extension = LogEntry-REL1_26-e6966ba
MediaWiki = 1.26.0
PHP = 5.5.9-1ubuntu4.14 (cgi-fcgi)
MySQL = 5.5.46-0ubuntu0.14.04.2