updating list item of a file using CSOM

I am using following code to copy a file from a document library to another. The file is copied and is there, but the fields will not be updated.

fileInfo = File.OpenBinaryDirect(srcClntCntxt, fileServerRelativeUrl);

using (ClientContext clntCntxt = ContextHelper.DestinationClientContex())
{
   Web web = clntCntxt.Web;
   clntCntxt.Load(web);
   clntCntxt.ExecuteQuery();

   string nLocation = web.ServerRelativeUrl.TrimEnd('/') + "/destLib/fileName";

    File.SaveBinaryDirect(clntCntxt, nLocation, fileInfo.Stream, true);
    File newFile = web.GetFileByServerRelativeUrl(nLocation);
    ListItem newFileItem = newFile.ListItemAllFields;
    clntCntxt.Load(newFile);
    clntCntxt.Load(newFileItem);
    clntCntxt.ExecuteQuery();

    newFile.CheckOut();
    newFileItem["MyComments"] = "test test"; //this is a multi line text 
    newFile.CheckIn(string.Empty, CheckinType.OverwriteCheckIn);
    newFileItem.Update();
    clntCntxt.ExecuteQuery();