Connection of several cameras: HIGHGUI ERROR: V4L: index XXX is not correct!

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Hello! Could any-one help me with the issue? I have the next code:

int CamID = 0;      // cams counter
int camFind = 0;    // counter for founded cameras

// looking for all cameras
for(int i = 0; i < 128; i++)
{
    std::string strDevName = "/dev/video" + std::to_string(i) + "\0";
    if (access(strDevName.c_str(), F_OK) == 0)
        camFind++;
}
printf("%d camera(s) founded. Trying to connect...\n", camFind);
// trying to connect to cameras
do
{
    VideoCapture tmpCam(CamID); // trying to get camera with ID CamID
    if (!tmpCam.isOpened())
    {
        CamID++;
        continue;
    }

    VideoCamera vCam;
    vCam.Init(tmpCam, vCams.size() + 1);
    vCams.push_back(vCam);      // add camera to vector
    CamID++;
}
while(vCams.size() < camFind);

But I've got the next output:

8 camera(s) founded. Trying to connect...
HIGHGUI ERROR: V4L: index 0 is not correct!
HIGHGUI ERROR: V4L: index 2 is not correct!
HIGHGUI ERROR: V4L: index 3 is not correct!
HIGHGUI ERROR: V4L: index 4 is not correct!
...
HIGHGUI ERROR: V4L: index 99 is not correct!

What is wrong? How can I determine indexes of my cameras?

Files in /dev:

/dev/video1
/dev/video8
/dev/video9
/dev/video10
/dev/video11
/dev/video12
/dev/video13
/dev/video14

Yes, I have eight cameras. Yes, all of them are connected correctly.

One note: if I restart my computer, I get the following set of files:

/dev/video0
/dev/video1
/dev/video2
/dev/video3
/dev/video4
/dev/video5
/dev/video6
/dev/video7

In this case all cameras will be connected by using of the previous code. WHY?! What is wrong?