REST API Not Working as Expected - api.ashx/v2/blogs.{json|xml}

I am making the following REST API call; however its returning blogs for ALL groups and ignored the group ID I am passing in, Is this a bug?

            var blogList = host.GetToXml(2, "blogs.xml", true, new RestGetOptions()
            {
                PathParameters = new System.Collections.Specialized.NameValueCollection {
                    {"GroupId", groupId.ToString() },
                    {"IncludeSubGroups", "false" }
                }

            });