video_capture.read() not working in my jetson nano[BUG]

[mmzz16]

Describe the issue
i was working on using my CSI camera with jetson nano and when i try to run the code from simple_camera.py i get the following error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'imshow'
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What version of L4T/JetPack
L4T/JetPack version: 4.5

What version of OpenCV
OpenCV version:4.1.1

Python Version
Python version if applicable: 3.6.9

To Reproduce
Steps to reproduce the behavior:
For example, what command line did you run?

i tried running the whole simple_camera.py but when i try to check it the problem starts with this line of code:
ret_val, frame = video_capture.read()

Expected behavior
A clear and concise description of what you expected to happen.

i wanted to connect to the csi camera and see a display window

Additional context
Add any other context about the problem here.