Hi again , Just want to share with you the solution of this problem , actually I had a problem on the size of the images wut made the training impossible , the image size was 1024*1024 on the validation file , although I resized data images on the training folder
that was the main problem so I hade to resize all images on the val folder to 256*256 and now it’s working .
the script of resizing the images size
from glob import glob
import cv2
from matplotlib import pyplot as plt
from tqdm import tqdm

!mkdir ./data/val
!mkdir ./data/val/A
!mkdir ./data/val/B
!mkdir ./data/val/label

file_list= glob("../ChangeDetection/data/LEVIR_CD/val_orig/A/*.png")
for file_name in tqdm(file_list):
    img_data = cv2.imread(file_name, cv2.IMREAD_UNCHANGED)
    img_resized_data = cv2.resize(img_data, (256, 256))
    dst_name = file_name.replace("_orig", "")
    cv2.imwrite(dst_name, img_resized_data)

thankx Srie Raam for Help