Android : Android Studio with opencv for android ndk, opencv header files not found

I'm getting to Android Studio for Android OpenCV developing, but when I compile the project which was ok in eclipse, I got this error:

D:\software\AndroidStudioProjects\CameraMe\openCVSamplefacedetection\src\main\jni\DetectionBasedTracker_jni.cpp:2:33: fatal error: opencv2/core/core.hpp: No such file or directory

I guess the headers for opencv was not found, but I don't know what's wrong.

Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

#OPENCV_CAMERA_MODULES:=off
#OPENCV_INSTALL_MODULES:=off
#OPENCV_LIB_TYPE:=SHARED
include D:\eclipse\OpenCV_2.4.9_android_sdk\sdk\native\jni\OpenCV.mk

LOCAL_SRC_FILES  := DetectionBasedTracker_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_LDLIBS     += -llog -ldl

LOCAL_MODULE     := detection_based_tracker

include $(BUILD_SHARED_LIBRARY)

Application.mk

APP_STL := gnustl_static
APP_CPPFLAGS := -frtti -fexceptions
APP_ABI := armeabi-v7a
APP_PLATFORM := android-8

DetectionBasedTracker_jni.cpp

#include <DetectionBasedTracker_jni.h>
#include <opencv2/core/core.hpp>
#include <opencv2/contrib/detection_based_tracker.hpp>
......