java.lang.IllegalArgumentException: View=DecorView@3c57d0a[FaceTrackerActivity] not attached to window manager
	at android.view.WindowManagerGlobal.findViewLocked(WindowManagerGlobal.java:581)
	at android.view.WindowManagerGlobal.removeView(WindowManagerGlobal.java:488)
	at android.view.WindowManagerImpl.removeViewImmediate(WindowManagerImpl.java:209)
	at android.app.Dialog.dismissDialog(Dialog.java:405)
	at android.app.Dialog.dismiss(Dialog.java:387)
	at com.entitcs.office_attendance.fragments.After_Taking_Group_Attendance$10.onPostExecute(After_Taking_Group_Attendance.java:999)
	at com.entitcs.office_attendance.fragments.After_Taking_Group_Attendance$10.onPostExecute(After_Taking_Group_Attendance.java:995)
	at android.os.AsyncTask.finish(AsyncTask.java:771)
	at android.os.AsyncTask.-$$Nest$mfinish(Unknown Source:0)
	at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:788)
	at android.os.Handler.dispatchMessage(Handler.java:111)
	at android.os.Looper.loopOnce(Looper.java:242)
	at android.os.Looper.loop(Looper.java:362)
	at android.app.ActivityThread.main(ActivityThread.java:8393)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:992)