java.lang.ClassNotFoundException: com.google.android.gms.games.Games

I tried implementing Google Services in my game, I've done every setup including the SHA 1 key but am getting this error from logcat each time i try signing in: 01-30 13:35:31.852 30868 30886 I Unity : CloudOnce.Internal.Providers.GooglePlayGamesCloudProvider:Initialize(Boolean, Boolean, Boolean) 01-30 13:35:31.852 30868 30886 I Unity : 01-30 13:35:31.859 30868 30886 E Unity : AndroidJavaException: java.lang.ClassNotFoundException: com.google.android.gms.games.Games 01-30 13:35:31.859 30868 30886 E Unity : java.lang.ClassNotFoundException: com.google.android.gms.games.Games 01-30 13:35:31.859 30868 30886 E Unity : at java.lang.Class.classForName(Native Method) 01-30 13:35:31.859 30868 30886 E Unity : at java.lang.Class.forName(Class.java:453) 01-30 13:35:31.859 30868 30886 E Unity : at com.unity3d.player.UnityPlayer.nativeRender(Native Method) 01-30 13:35:31.859 30868 30886 E Unity : at com.unity3d.player.UnityPlayer.access$300(Unknown Source:0) 01-30 13:35:31.859 30868 30886 E Unity : at com.unity3d.player.UnityPlayer$e$1.handleMessage(Unknown Source:95) 01-30 13:35:31.859 30868 30886 E Unity : at android.os.Handler.dispatchMessage(Handler.java:102) 01-30 13:35:31.859 30868 30886 E Unity : at android.os.Looper.loop(Looper.java:214) 01-30 13:35:31.859 30868 30886 E Unity : at com.unity3d.player.UnityPlayer$e.run(Unknown Source:20) Any help on this will be appreciated.