Exceptions while working

Hello! I'm working on realization of XWikiStoreInterface to storing pages and attachments in svn (JavaSvn lib). Every time after launch (and while working) i see two exceptions: "java.lang.NullPointerException at com.xpn.xwiki.stats.impl.XWikiStatsServiceImpl.findVisitByIPUA(XWikiStatsServiceImpl.java:432)" and "java.lang.NullPointerException at com.xpn.xwiki.stats.impl.XWikiStatsServiceImpl.notify(XWikiStatsServiceImpl.java:216)" In what a problem? Where is a mistake? Big thanks. Sorry for my terrible english.