Hi Shamim,
Did you make sure the domain where you run your experiment matches the one you reference in the line header("Access-Control-Allow-Origin: https://my.domain.xyz");? It should be https://farm.pcibex.net if you are running your experiment on the farm (like here)
Feel free to share a link to your experiment with me, either here or at support@pcibex.net, so I can help you troubleshoot the issue
Jeremy