System.NotImplementedException: 'The method or operation is not implemented.' on ipfs.Name.PublishAsync

[hsafarigithub]

hi
How to fix the following code problem:

private async void Button1_Click(object sender, EventArgs e)
{
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;
string passphrase = "this is not a secure pass phrase";
var ipfs = new IpfsEngine(passphrase.ToCharArray());//"https://ipfs.infura.io:5001"
var fsn = await ipfs.FileSystem.AddTextAsync("salam hossein");
var sns = await ipfs.Name.PublishAsync((string)fsn.Id, false);
MessageBox.Show((string)sns.NamePath);
}