acquiring images from simulation?

Hi, i have a problem with acquiring images from my simulation. I think the problem is in the script i use to manage this, as it works fine and is fluid until i enable a SaveVideo button. Below i write the script i use for this task:

using UnityEngine; using System.Collections.Generic; public class CamerasManager : MonoBehaviour { public bool enableVideoSave; public string folder = "AcquisitionVideo"; public int frameRate = 25; public List cameras = new List();

// initialisation void Start() {

   if(enableVideoSave) {

      Time.captureFramerate = frameRate;
      if(cameras.Count > 0) {

         // create one main folder which will contain a sub folder for each camera 
         folder = folder + System.DateTime.Now.ToString("_yyyy-MM-dd_HH-mm-ss");
         if(System.IO.Directory.Exists(folder)) {
            System.IO.Directory.Delete(folder, true);
         }
         System.IO.Directory.CreateDirectory(folder);

         // create sub folder for each camera
         for(int i = 0; i < cameras.Count; ++i) {
            if(cameras[i].Camera) {
               cameras[i].Folder = string.Format("{0}/{1}_{2}x{3}_{4}fps",
                                                  folder,
                                                  cameras[i].Name,
                                                  cameras[i].Camera.rect.width,
                                                  cameras[i].Camera.rect.height,
                                                  frameRate);
               System.IO.Directory.CreateDirectory(cameras[i].Folder);
            }
         }
      }
   }

}

//function called after Update() void LateUpdate() {

   if(enableVideoSave) {
      // for each camera
      for(int i = 0; i < cameras.Count; ++i) {
         if(cameras[i].Camera) {
            RenderTexture rt = new RenderTexture((int) cameras[i].Camera.rect.width, (int) 
            cameras[i].Camera.rect.height, 24);
            cameras[i].Camera.targetTexture = rt;

            rt.antiAliasing = 8;

            Texture2D screenShot = new Texture2D(rt.width, rt.height, TextureFormat.RGB24, false);
            cameras[i].Camera.Render();
            RenderTexture.active = rt;
            screenShot.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
            cameras[i].Camera.targetTexture = null;
            RenderTexture.active = null; 
            Destroy(rt);
            
            byte[] bytes = screenShot.EncodeToPNG();

            string filename = string.Format("{0}/frame_{1:D04}.png", cameras[i].Folder, Time.frameCount);
            System.IO.File.WriteAllBytes(filename, bytes); 
         }
      }
   }

} }

[System.Serializable]

public class CameraType {

    public string Name;
    public Camera Camera;
   public string Folder;
   public CameraType(string _Name) {
   Name = _Name;

} }

I also attach a screen with the errors. Thanks in advance