C#ASP导入Excel文件报错了 ?报错

一开始，建了一个测试网站，能导入Excel表格，没有报错，然后并入到其他程序时出错了，因为用到的Microsoft.Jet.OLEDB.4.0好像是32位组件，就在iis那里启用了32位应用程序，然后就报错了， (Microsoft Jet 数据库引擎打不开文件''。 它已经被别的用户以独占方式打开，或没有查看数据的权限。) 然后把测试网站也放到iis里面去，也报错了，没用iis就不报错，怎么回事啊？导入代码如下:
protected void btnGetTableName_Click(object sender, EventArgs e)
{
this.ddlTables.Items.Clear();
string sFileName = this.fuMainOne.PostedFile.FileName.ToString();
_sFileName = sFileName;
if (sFileName.Length == 0)
{
ClientScript.RegisterStartupScript(this.GetType(), "", "alert('您没有选择要求导入的Excel文件！')");
return;
}
//sFileName = this.hiddenContent1.Value;
using (OleDbConnection oledbConn = new OleDbConnection())
{
try
{
oledbConn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + sFileName + ";Extended Properties=Excel 8.0;";
oledbConn.Open();
using (DataTable dtOledb = oledbConn.GetSchema("Tables"))
{
using (DataTableReader dtReader = new DataTableReader(dtOledb))
{
while (dtReader.Read())
{
this.ddlTables.Items.Add(dtReader["TABLE_NAME"].ToString());
}
}
}
string SQLString = "select * from [" + ddlTables.SelectedValue.ToString() + "]";
OleDbCommand DBCommand = new OleDbCommand(SQLString, oledbConn);
IDataReader DBReader = DBCommand.ExecuteReader();
GridView1.DataSource = DBReader;
GridView1.DataBind();
DBReader.Close();
oledbConn.Close();
}
catch
{
ClientScript.RegisterStartupScript(this.GetType(), "", "alert('Excel文件格式不正确！')");
return;
}
}
}