I got this error V4L/v4L2

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HIGHGUI ERROR: V4L/V4L2: VIDIOC_S_CROP OpenCV Error: Assertion failed (k STD_VECTOR_MAT) in getMat, file /home/qt/opencv/OpenCV/OpenCV/opencv-2.4.8/modules/core/src/matrix.cpp, line 988 terminate called after throwing an instance of 'cv::Exception' what(): /home/qt/opencv/OpenCV/OpenCV/opencv-2.4.8/modules/core/src/matrix.cpp:988: error: (-215) k STD_VECTOR_MAT in function getMat

The program has unexpectedly finished.