How to update shipment total weight through API

Hi,

I'm trying to update shipment total weight through the API but keep getting the following error, yet I can update the weight through the site. Can anyone tell me what I'm doing wrong?

{"status":"failure","errors":["Can't edit a paid shipment"],"request_id":"5c10b2e5dbbe3aa9db1119241807524b","timestamp":"2022-10-08T05:40:12.110Z"}

this is my code:

Your help would be greatly appreciated

Thanks