Android SDK captured incorrect local time

I have set the timezone of the server to UTC and I am using the Android app with Android SDK installed in timezone UTC+8. When tracking the usage of Android apps, all local time (visitor_localtime field in piwik_log_visit table) in Piwik log are recorded the same as UTC time (visit_first_action_time field in piwik_log_visit table). Do anyone have idea what is going wrong?