求助！我从前台上传一个execl表格，在后台反序列化出现“其他信息: 输入流是无效的二进制格式。开始内容(以字节为单位)是: 68-74-74-70-3A-2F-2F-62-6C-6F-67-2E-63-73-64-6E-2E...”错误。。。。。
代码是：
public string ImportCompany()
{
HttpPostedFileBase table = Request.Files["table"];
ie.ExcelToDataTable(table.InputStream);
return null;
}

public List<object> status { get; set; }

public bool ExcelToDataTable(Stream sm)
{
status = new List<object>();
status.Add(2);
status.Add("正在读取数据......");
byte[] buff = new byte[sm.Length];
sm.Read(buff, 0, (int)sm.Length);
BinaryFormatter b = new BinaryFormatter();
b.TypeFormat = System.Runtime.Serialization.Formatters.FormatterTypeStyle.TypesAlways;
DataTable t = (DataTable)b.Deserialize(new MemoryStream(buff));
return true;
}