problem with Snapshot on webcam

Hi everyone, I have problem with the snapshot syntax. so, basically, i have this project which use laser distances and camera/webcam for detection. the process is something like this and it is in real time: when laser sensors detect the obstacles, it will instruct camera to get a snapshot of the scenes. Then, as the laser sensors move closer to the obstacles, it will take another snapshot of the scenes. so, the problem is, i always get similar image between snapshot scenes 2 and snapshot scenes 1. I do not know what happen, seems like the camera stuck in viewing the scenes. The snapshot scenes 2 and Snapshot scenes 1 supposed to be different image due to different distance detected. can somebody tell me what is going on? hope you guys understand the problem.

Thank you

[Image Analyst]

Understood, but there's no way we can fix it. We don't have your code or your laser/camera setup.

[muhammad faiz]

 end
Radio = serial('COM3','BaudRate',9600); % from the distance sensor
fopen(Radio);
Nvalues=1000000000;
Mvalues=1000000000;
k=0;
w=0;
cam=webcam('ManyCam Virtual Webcam');
cam.Resolution='640x360';
while k<Nvalues
Lidar_distance = fscanf(Radio,'%f');
if (Lidar_distance<=8.1)
    Image_Ref=snapshot(cam);
     while w<Mvalues
             second_distance=fscanf(Radio,'%f');
         if (second_distance<=7.1)
            Image_Current=snapshot(cam);
            break;
         end
         display(second_distance)
         w=w+1;
     end
end
display(Lidar_distance)
k=k+1;
end

______________________ this is my code (simplified version)