java - Activity class does not exist? -

i trying make game switches activity whenever user clicks button. trying use application class use variable throughout of activities, variable current time in milliseconds when app starts.

then, in game on screen want find current time again, , subtract currenttime new current time. should give me amount of time user has been playing game. after finding value; want display on screen. problem is, getting following error:

starting: intent { act=android.intent.action.main cat=  [android.intent.category.launcher]     cmp=com.example.username.buttonsmasher/.main_menu } error type 3 error: activity class  {com.example.username.buttonsmasher/com.example.username.buttonsmasher.main_menu} not exist. 

here main_menu oncreate activity, set currenttimemillis variable currenttime, mycurrenttime class:

here gameover screen display total time spent on app:

here android manifest file:

<?xml version="1.0" encoding="utf-8"?>     <manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.example.username.buttonsmasher" >   <application     android:allowbackup="true"     android:icon="@mipmap/ic_launcher"     android:label="@string/app_name"     android:theme="@style/apptheme" >     <activity         android:name=".main_menu"         android:label="@string/app_name" >         <intent-filter>             <action android:name="android.intent.action.main" />              <category android:name="android.intent.category.launcher" />         </intent-filter>     </activity>     <activity         android:name=".left_up"         android:label="@string/title_activity_left__up" >     </activity>     <activity         android:name=".left_center"         android:label="@string/title_activity_left__center" >     </activity>     <activity         android:name=".left_down"         android:label="@string/title_activity_left__down" >     </activity>     <activity         android:name=".center_up"         android:label="@string/title_activity_center__up" >     </activity>     <activity         android:name=".center_center"         android:label="@string/title_activity_center__center" >     </activity>     <activity         android:name=".center_down"         android:label="@string/title_activity_center__down" >     </activity>     <activity         android:name=".right_up"         android:label="@string/title_activity_right__up" >     </activity>     <activity         android:name=".right_center"         android:label="@string/title_activity_right__center" >     </activity>     <activity         android:name=".right_down"         android:label="@string/title_activity_right__down" >     </activity>     <activity         android:name=".gameover"         android:label="@string/title_activity_game_over" >     </activity> </application>  <application>android:name=".mycurrenttime"</application>  </manifest> 

please me why error happening. reason posted methods of app because know issue time. app running fine untill today, when tried add time display. appreciate help, , have been trying solve issue on 2 hours now! thank much, , if need more information, feel free let me know. any feedback appreciated.

thanks!

ah, didn't see second application tag. don't think can :)

place name property inside first application tag , remove second one.