video capture for 2 cameras

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Hi i have a question today: I have 2 cameras and want to use the second to capture video.I use the same code program and the same usb cable which has been use for the first one.But i can capture the video and when compile the program i got this error:

[ INFO:0] global C:\build\master_winpack-build-win64-vc14\opencv\modules\videoio\src\backend_plugin.cpp (340) cv::impl::getPluginCandidates Found 2 plugin(s) for GSTREAMER

**[ INFO:0] global C:\build\master_winpack-build-win64-vc14\opencv\modules\videoio\src\backend_plugin.cpp (172) cv::impl::DynamicLib::libraryLoad load C:\opencv\build\x64\vc14\bin\opencv_videoio_gstreamer411_64.dll => FAILED

[ INFO:0] global C:\build\master_winpack-build-win64-vc14\opencv\modules\videoio\src\backend_plugin.cpp (172) cv::impl::DynamicLib::libraryLoad load opencv_videoio_gstreamer411_64.dll => FAILED**

And the code program is as below:

#include "opencv2/opencv.hpp"
using namespace cv;
int main(int, char**)
{
    VideoCapture cap(1);

    if (!cap.isOpened())
        return -1;
    while (1)
    {
        Mat frame;
        cap.read(frame);
        imshow("video", frame);

        if (waitKey(30) == 's')
        {
            break;
        }
    }
    return 0;
}

I have install gstreamer so i can do this with the first camera but i dont know what is that problem about? Can anyone tell me a sulution for this? Thank you.