external table is not in expected format excel 2010.

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SharePoint2010

I have to upload a excel sheet in document library and have to show all the details of list in grid view. But I am getting error "external table is not in expected format:.

My code is

void uploadDocument()
{

    try
    {
        string publicFSdocLibrary = "PublicFSdoc";

        if (uploadDoc.HasFile)
        {
            SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                using (SPSite oSite = new SPSite("http://chdsez301298d:1000/sites/Test/"))
                //using (SPSite oSite = new SPSite(SPContext.Current.Site.ID))
                {
                    using (SPWeb myWeb = oSite.OpenWeb())
                    {
                        SPListItem lstItem = SPContext.Current.ListItem;
                        myWeb.AllowUnsafeUpdates = true;

                        //SPList docList = myWeb.Lists[docLibrary];
                        SPFolder finalDocument = myWeb.Folders[publicFSdocLibrary];
                        // Prepare to upload
                        Boolean replaceExistingFiles = true;
                        string fileName = Path.GetFileName(uploadDoc.FileName);
                        filePath = Path.GetFullPath(uploadDoc.PostedFile.FileName);
                        // string newFilePath = getFilePath(filePath);
                        FileStream fileStream = System.IO.File.OpenRead(filePath);
                        // Upload document
                        SPFile spfile = finalDocument.Files.Add(getFileName(), fileStream, replaceExistingFiles);
                        SPListItem item = spfile.Item;
                        item["RequestNo"] = generateRequestNo();
                        item["AssessmentType"] = "Financial Solvency";
                        // Commit all changes
                        item.Update();
                        //Update document url to Assessment request list                               
                        myWeb.AllowUnsafeUpdates = false;
                    }
                }
            });
        }

    }
    catch (Exception ex)
    {
        ex.Message.ToString();

    }

}

string getFileName()
{
    string newFileName = generateRequestNo() + ".xlsx";
    return newFileName;
}


void btnUpload_Click(object sender, EventArgs e)
{
    uploadDocument();
    getExcelData();
    //savePublicFS();
    //addAssesmentWfRequest();
    //CloseForm();
    //Page.ClientScript.RegisterStartupScript(this.GetType(), "close", "window.close();", true);
    
}

void getExcelData()
{
    try
    {
        if (uploadDoc.HasFile)
        {

            OleDbConnection conn = new OleDbConnection();
            OleDbCommand cmd = new OleDbCommand();
            OleDbDataAdapter da = new OleDbDataAdapter();
            DataSet ds = new DataSet();
            //string sheetName = "Sourcing Questionnaire";
            string query = null;
            string connString = "";
            string fileName = Path.GetFileName(uploadDoc.FileName);
            string strFileType = System.IO.Path.GetExtension(uploadDoc.FileName).ToString().ToLower();
            string strNewPath = filePath;

            //Connection String to Excel Workbook
            if (strFileType.Trim() == ".xls")
            {
                connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strNewPath + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
            }
            else if (strFileType.Trim() == ".xlsx")
            {
                connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + strNewPath + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
            }
           // query = "SELECT * FROM [" + sheetName + "$]";
            query = "SELECT * FROM [abc$]";
            //Create the connection object
            conn = new OleDbConnection(connString);
            //Open connection
            if (conn.State == ConnectionState.Closed) conn.Open();
            //Create the command object
            cmd = new OleDbCommand(query, conn);
            da = new OleDbDataAdapter(cmd);
            ds = new DataSet();
            da.Fill(ds);
            gvdetails.DataSource = ds.Tables[0];
            gvdetails.DataBind();
            da.Dispose();
            conn.Close();
            conn.Dispose();
            //return ds;

        }            

    }
    catch (Exception)
    {

        throw;
    }
}

private String generateRequestNo()
{
    try
    {
        String requestNo = String.Empty;
        if (txtSupplierName.Text.Length <= 4)
        {
            requestNo = txtSupplierName.Text
                          + "-" + requestNumber()
                          + DateTime.Today.ToString("ddMMyyyy");
        }
        else
        {
            requestNo = txtSupplierName.Text.Substring(0, 4)
                              + "-" + requestNumber()
                              + DateTime.Today.ToString("ddMMyyyy");
        }
        return requestNo;
    }
    catch (Exception)
    {
        throw;
    }
}
private String requestNumber()
{
    try
    {
        String number = String.Empty;
        number = "FS-";
        return number;
    }
    catch (Exception)
    {
        throw;
    }
}

and I am getting error in getExcelData() method at line cmd = new OleDbCommand(query, conn);

Please help me as I struck here since last week.