کار نکردن activity

ارورها

11-01 11:14:52.007 8345-8349/? E/art: Failed sending reply to debugger: Broken pipe
11-01 11:14:54.201 8345-8345/com.example.asus.recyclerview5 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.asus.recyclerview5, PID: 8345
android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.asus.recyclerview5/com.example.asus.recyclerview5.MainActivity2}; have you declared this activity in your AndroidManifest.xml?
at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1805)
at android.app.Instrumentation.execStartActivity(Instrumentation.java:1523)
at android.app.Activity.startActivityForResult(Activity.java:4225)
at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:54)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:75)
at android.app.Activity.startActivityForResult(Activity.java:4183)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:708)
at android.app.Activity.startActivity(Activity.java:4522)
at android.app.Activity.startActivity(Activity.java:4490)
at com.example.asus.recyclerview5.MainActivity$1.onClick(MainActivity.java:25)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

سلام 

اکتیویتی MainActivity2  در AndroidManifest.xml معرفی نکردید بخاطر همین موقع باز کردنش خطا میده