Unknown authentication scheme when liking post (LinkedIn API) - linkedin

Question

Below goal is to like a post!
I get an error when trying to "Like" a post with the REST API (LinkedIn)
I have created an accesstoken with all scopes:
scope=w_messages+rw_company_admin+rw_nus+r_emailaddress+r_basicprofile+rw_groups+r_fullprofile+r_network+r_contactinfo
I can retreive comments from posts with the accesstoken which tell us that I have set it up correctly as a base.
However when I try to like a comment with the below code (just after in the same code where I have collected a comment), I receive this error:
"unknown authentication scheme"
I wonder why I can't like a post when I have set all scopes and I also have them checked in my application settings. Also notice that the postID is correct as I can retreive the comments for the post?
Thank you!
String accessToken = "MYLONGTOKEN"; //Just dummy example
String postID = "g-123456-S-123456789"; //Just dummy example
String requestUrl = "https://api.linkedin.com/v1/posts/" + postID + "/relation-to-viewer/is-liked&oauth2_access_token=" + accessToken;
RestSharp.RestClient rc = new RestSharp.RestClient();
RestSharp.RestRequest request = new RestSharp.RestRequest(requestUrl, RestSharp.Method.PUT);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("x-li-format", "json");
request.RequestFormat = RestSharp.DataFormat.Json;
restResponse = (RestSharp.RestResponse)rc.Execute(request);
responseStatus = restResponse.ResponseStatus;
//unknown authentication scheme
MessageBox.Show(restResponse.Content.ToString());

Answer 1

I found a solution which seems to work. The additional and replacement code is:
//Comment this post
requestUrl = "https://api.linkedin.com/v1/posts/" + postID + "/comments?oauth2_access_token=" + accessToken;
var comment = new
{
text = "This is a comment!"
};
rc = new RestSharp.RestClient();
request = new RestSharp.RestRequest(requestUrl, RestSharp.Method.POST);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("x-li-format", "json");
request.RequestFormat = RestSharp.DataFormat.Json;
request.AddBody(comment);
restResponse = (RestSharp.RestResponse)rc.Execute(request);
responseStatus = restResponse.ResponseStatus;
MessageBox.Show(responseStatus.ToString() + "," + restResponse.Content.ToString());