UploadFileCollection files = AspnetUpload.GetUploadFiles("file1") 为空，取不到路径

[qzs1010]

UploadFileCollection files = AspnetUpload.GetUploadFiles("file1") 为空，取不到路径
在调试时候可以，但是 IIS下面运行却不行呢，，是什么原因呢，请大侠帮帮忙。
代码如下

UploadFileCollection files = AspnetUpload.GetUploadFiles("file1");
foreach (UploadFile file in files)
{
if (file != null)
{

string filename = DateTime.Now.ToString("yyyyMMddHHmmss") + "-" + ran.Next(100, 999);

string extension = Path.GetExtension(file.get_FileName());

newname = fpath + "\\" + filename + extension;
file.SaveAs(newname);
msg = db.AddData("eip_tm_downloaddocument", "downloaddocumentname,documentid,downloaddocumentaddress,downloaddocumenttype", "'" + this.downloaddocumentname.Text + "','" + id + "','" + newname + "','" + state + "'", "downloaddocumentid");
}
else
{
msg = "上传文件为空，请你选择一个上传文件";
}
}