不能上传视频文件

try
        {
            string sql = "";
            if (isVS == "tb_Sound")                        //判断教程是否是语音类型
            {
                //判断用户上传的文件类型
                if (FileUpload1.FileName.Substring(FileUpload1.FileName.LastIndexOf(".") + 1) == "mp3")
                {
                    //判断用户上传的语音教程是否存在
                    if (!File.Exists(Server.MapPath(".") + "\\Sound\\" + this.FileUpload1.FileName))
                    {
                        sql = "insert into tb_Sound(SoundType,SoundName,SoundUrl,ClickSum,SoundContent,Name) values('" + typ + "','" + vsname + "','" + this.FileUpload1.FileName + "','" + clicksum + "','" + content + "','" + name + "')";
                        //设置路径用于保存上传的语音
                        Path = Server.MapPath("./") + "Sound" + "\\" + this.FileUpload1.FileName;
                        if (mydo.adlData(sql))
                        {
                            //将文件保存到指定位置
                            FileUpload1.PostedFile.SaveAs(Path);
                            Page.RegisterStartupScript("true", "<script>alert('上传成功！')</script>");
txtName.Text="";
txtContent.Text="";
                        }
                        else
                        {
                            Page.RegisterStartupScript("true", "<script>alert('上传失败！')</script>");
                        }
                    }
                    else
                        Page.RegisterStartupScript("false", "<script>alert('教程名称已经存在！')</script>");
                }
                else
                      RegisterStartupScript("false", "<script>alert('只能上传mp3类型！')</script>");
            }
            else
            {
                //判断用户上传的文件类型
                string type = FileUpload1.PostedFile.FileName.Substring(FileUpload1.FileName.LastIndexOf(".") + 1);
                if (type == "rmvb"||type == "wmv"  )
                {
                    //判断用户上传的视频教程是否存在
                    if (!File.Exists(Server.MapPath(".") + "\\Video\\" + this.FileUpload1.FileName))
                    {
                        sql = "insert into tb_Video(VideoType,VideoName,VideoUrl,ClickSum,VideoContent,Name) values(" + typ + ",'" + vsname + "','" + this.FileUpload1.FileName + "'," + clicksum + ",'" + content + "','" + name + "')";
                        Path = Server.MapPath("~/") + "Video" + "\\" + this.FileUpload1.FileName;
                        if (mydo.adlData(sql))
                        {
                            FileUpload1.PostedFile.SaveAs(Path);
                            Page.RegisterStartupScript("true", "<script>alert('上传成功！')</script>");
txtName.Text="";
txtContent.Text="";
                        }
                        else
                        {
                            Page.RegisterStartupScript("true", "<script>alert('上传失败！')</script>");
                        }
                    }
                    else
                    {
                        Page.RegisterStartupScript("false", "<script>alert('教程名称已经存在！')</script>");
                    }
                }
                else
                  RegisterStartupScript("false", "<script>alert('只能上传wmv类型！')</script>");
            }
        }
        catch (Exception ex)
        {
            Page.RegisterStartupScript("false", "<script>alert('上传教程不能为空！')</script>");
        }
    }
为什么mp3格式的文件能上传，而视频却不能上传