Can't upload an image to imgur with asp.net

I am working on project that I need to upload image to imgur.com, I wrote the code but it didn't work when came to posting part! any suggestions?

 private async Task<string> UploadImageAsync(string imageDataBase64String)
    {
        client = new HttpClient();
        client.BaseAddress = new Uri("https://api.imgur.com/3/");
        client.DefaultRequestHeaders.Add("Authorization", "Client-id " + ClientID);
        HttpContent contentPost = new StringContent(imageDataBase64String);
        var response = await client.PostAsync("image", contentPost);
        response.EnsureSuccessStatusCode();
        var responseContent = await response.Content.ReadAsStringAsync();
        var model = new JavaScriptSerializer().Deserialize<dynamic>(responseContent);
        var imageLink = model["data"]["link"];
        return imageLink;
    }

Solution

I'm working on similar project and here is how I did it.

Create a view models for imgur response:

public class ImgurResponseViewModel
{
    public ImgurImageDataViewModel Data { get; set; }
    public bool Success { get; set; }
    public int Status { get; set; }
}

Create a view models for image data:

public class ImgurImageDataViewModel
{
    public string Id { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public string Datetime { get; set; }
    public string Type { get; set; }
    public bool Animated { get; set; }
    public int Width { get; set; }
    public int Height { get; set; }
    public int Size { get; set; }
    public int Views { get; set; }
    public int Bandwidth { get; set; }
    public string Ddeletehash { get; set; }
    public string Section { get; set; }
    public string Link { get; set; }
    public string Account_url { get; set; }
    public int Aaccount_id { get; set; }
}

And this is the code for uploading:

private async Task<string> UploadImageAsync(string imageDataBase64String)
{
    byte[] response;
    using (var client = new WebClient())
    {
        string clientID = "YourClientID";
        client.Headers.Add("Authorization", "Client-ID " + clientID);
        var values = new NameValueCollection { { "image", imageDataBase64String } };
        response = await client.UploadValuesTaskAsync("https://api.imgur.com/3/upload", values);
    }

    var result = JsonConvert.DeserializeObject<ImgurResponseViewModel>(Encoding.ASCII.GetString(response));

    return result.Data.Link;
}

I hope this will help you.