failed to determine Model class name, are you sure models have been instrumented?

When i visit history page that use mysql DB, i get this exception!

```
Caused by:
org.javalite.activejdbc.DBException: failed to determine Model class name, are you sure models have been instrumented?
at org.javalite.activejdbc.Model$ClassGetter.getClassName(Model.java:2342)
at org.javalite.activejdbc.Model.getClassName(Model.java:2315)
at org.javalite.activejdbc.Model.getDaClass(Model.java:2307)
at org.javalite.activejdbc.Model.getMetaModel(Model.java:58)
at org.javalite.activejdbc.Model.findAll(Model.java:1848)
at com.deem.zkui.dao.Dao.fetchHistoryRecords(Dao.java:65)
at com.deem.zkui.controller.ChangeLog.doGet(ChangeLog.java:51)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder$NotAsyncServlet.service(ServletHolder.java:1395)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:755)
```