Openfire 3.10.2 can't start "Load Statistic" plugin

I have updated my openfire server from 3.9.3 to 3.10.2, then I found that the plugin “Load Statistic” did not work anymore.

I checked log and it says :

2015.08.03 13:57:57 org.jivesoftware.openfire.container.PluginManager - Error loading plugin: /opt/openfire/plugins/loadstats

java.lang.NoClassDefFoundError: org/apache/mina/common/IoService

| at org.jivesoftware.openfire.plugin.StatisticPlugin.initializePlugin(StatisticPlug in.java:40)

| at org.jivesoftware.openfire.container.PluginManager.loadPlugin(PluginManager.java :477)

| at org.jivesoftware.openfire.container.PluginManager.access$300(PluginManager.java :76)

| at org.jivesoftware.openfire.container.PluginManager$PluginMonitor.run(PluginManag er.java:1068)

| at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)

| at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351)

| at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178)

| at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301 (ScheduledThreadPoolExecutor.java:178)

| at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Schedu ledThreadPoolExecutor.java:293)

| at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)

| at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)

| at java.lang.Thread.run(Thread.java:722)

Caused by: java.lang.ClassNotFoundException: org.apache.mina.common.IoService

| at java.net.URLClassLoader$1.run(URLClassLoader.java:366)

| at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

| at java.security.AccessController.doPrivileged(Native Method)

| at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

| at java.lang.ClassLoader.loadClass(ClassLoader.java:423)

| at java.lang.ClassLoader.loadClass(ClassLoader.java:356)

| … 12 more

Plugin’s version is 1.2.0.

I wanna to know how to repair this problem.

Thanks.