WebClient.DownloadData失败?

Question

catch报An exception occurred during a WebClient request.错误
代码如下：
string url=http://act.lexun.com/ztapp/Templates/release/cc1d2175_3506_44b2_be7a_b0add0bb5f5f.zip
byte[] buffer = new WebClient { Credentials = CredentialCache.DefaultCredentials }.DownloadData(url);
这里直接跳到异常。
zip压缩包只有2M大小。