I got opencv link error

[diamondcm]

[armeabi-v7a] StaticLibrary : libdlib.a
[armeabi-v7a] StaticLibrary : libjni_common.a
[armeabi-v7a] StaticLibrary : libminiglog.a
[armeabi-v7a] SharedLibrary : libandroid_dlib.so
/home/ui/workspace/dlib-android-master/third_party/opencv/jni/include/opencv2/core/cvstd.inl.hpp:81: error: undefined reference to 'cv::String::allocate(unsigned int)'
jni/jni_detections/jni_pedestrian_det.cpp:109: error: undefined reference to 'cv::imread(cv::String const&, int)'
/home/ui/workspace/dlib-android-master/third_party/opencv/jni/include/opencv2/core/cvstd.hpp:667: error: undefined reference to 'cv::String::deallocate()'
/home/ui/workspace/dlib-android-master/third_party/opencv/jni/include/opencv2/core/mat.inl.hpp:682: error: undefined reference to 'cv::Mat::deallocate()'
and so on

like this. I run envsetup.
Do I miss any setup steps?
Thanks.