Updating Content via REST API

I am having trouble updating content via the REST API.  The end goal is to update the tags on a variety of content (wikis, blogs, files, etc).  I was unable to get that to work, so I've been just trying to update the body of a blog post and that isn't working either.  My first attempt followed the Update Blog Post REST Endpoint API documentation:

var response = host.PutToDynamicAsync(2, "blogs/{blogid}/posts/{id}.json", false, new RestPutOptions {
    AdditionalHeaders = headers,
    PathParameters = new System.Collections.Specialized.NameValueCollection {
        {"blogid", dataRow("SectionId")},
        {"id", dataRow("ContentId")},
        {"body", "body updated"}    
    }
});

I then saw another question here that said you need to use a post with a rest-method header of put, so I tried the below code:

headers.Add("Rest-Method", "PUT");
var response = host.PostToDynamicAsync(2, "blogs/{blogid}/posts/{id}.json", false, new RestPostOptions {
    AdditionalHeaders = headers,
    PathParameters = new System.Collections.Specialized.NameValueCollection {
        {"blogid", dataRow("SectionId")},
        {"id", dataRow("ContentId")},
        {"body", "body updated"}    
    }
});

Both sets of code do not result in any errors from the response, however they also don't successfully update the body of the blog.  Any ideas what I'm doing wrong?