C# Add new comment

Dear all,
we are developing a simple client to read our Jira cloud.

At the moment we can read correctly the information, but when we try to put a new comment with command
await issue.AddCommentAsync(“from our client”);
we receive an exception:
’Unable to add comment due to missing author field.'

We use the c# into Visual Studio 2019 community and we installed Atlassian.SDK v12.1.1. We are following the documentation at page https://bitbucket.org/farmas/atlassian.net-sdk/src/b4dee0050fd5d31f1b237c59113355137d1dc477/docs/how-to-use-the-sdk.md at section Comments

Have you some suggestions?

Thanks in advance