Could not find installable ISAM.

I receive the error message "Could not find installable ISAM." When I try to open an Excel file in my C# code behind of an aspx page. The code is:

// Create connection string variable. Modify the "Data Source"
        // parameter as appropriate for your environment.
        String sConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;" +
            "Data Source=" + Server.MapPath("template.xlsx") + ";" +
            "Extended Properties=Excel 8.0;HDR=NO;IMEX=1";

        // Create connection object by using the preceding connection string.
        OleDbConnection objConn = new OleDbConnection(sConnectionString);

        // Open connection with the database.
        objConn.Open();

        // The code to follow uses a SQL SELECT command to display the data from the worksheet.

        // Create new OleDbCommand to return data from worksheet.
        OleDbCommand objCmdSelect = new OleDbCommand("SELECT * FROM Sheet1", objConn);

        // Create new OleDbDataAdapter that is used to build a DataSet
        // based on the preceding SQL SELECT statement.
        OleDbDataAdapter objAdapter1 = new OleDbDataAdapter();

        // Pass the Select command to the adapter.
        objAdapter1.SelectCommand = objCmdSelect;

        // Create new DataSet to hold information from the worksheet.
        DataSet objDataset1 = new DataSet();

        // Fill the DataSet with the information from the worksheet.
        objAdapter1.Fill(objDataset1, "ExcelData");

        // Bind data to DataGrid control.
        GridView2.DataSource = objDataset1.Tables[0].DefaultView;
        GridView2.DataBind();

        // Clean up objects.
        objConn.Close();