deep insert is not working

hello everyone,

I am using cloud Business central. I am trying to post the Sales header and sales lines In one API request. this is below what have done so far 

I created the web service from sales order page 42 

second, I used the following request, with the "expand" parameter


the post request is going with our errors, but no lines are created. though 

get request is working fine and retrieve header and lines,