Errors in TVL1 cuda optical flow (Bug #4441)

Hi,
I try TVL1 in opencv, and I met this errors.
I do not know whether this is not implemented in cuda yet or a bug.
My function is very simple.
void myCudaOpticalFlowDual_TVL1(const Mat prev_grey, const Mat grey, Mat& flow) {
// create algo with default parameters
Ptr<cuda::OpticalFlowDual_TVL1> tvl1Flow = cuda::OpticalFlowDual_TVL1::create();
tvl1Flow->calc(prev_grey, grey, flow);
MedianBlurFlow(flow, 5);
}

And the error is:

Starting /home/beahacker/Desktop/opencv-workspace/motion_based_foreground_detection/src-build/DenseTrackViz...
OpenCV version: 3.0.0-dev
OpenCV Error: The function/feature is not implemented (getGpuMat is available only for cuda::GpuMat and cuda::HostMem) in getGpuMat, file /home/beahacker/Downloads/opencv-new/opencv/modules/core/src/matrix.cpp, line 1437
terminate called after throwing an instance of 'cv::Exception'
what(): /home/beahacker/Downloads/opencv-new/opencv/modules/core/src/matrix.cpp:1437: error: (-213) getGpuMat is available only for cuda::GpuMat and cuda::HostMem in function getGpuMat

The program has unexpectedly finished.
/home/beahacker/Desktop/opencv-workspace/motion_based_foreground_detection/src-build/DenseTrackViz crashed

Thank you,
Hope to receive your response soon.