No grid lines when exporting to excel

Hello Experts,

I am using crystal report to export to excel.

Code:

---

Dim excelFormatOpts As New ExcelFormatOptions
crReport.ExportOptions.ExportFormatType = CrystalDecisions.Shared.ExportFormatType.Excel
excelFormatOpts.ExcelUseConstantColumnWidth = False
excelFormatOpts.ExcelTabHasColumnHeadings = False
crReport.ExportOptions.FormatOptions = excelFormatOpts
strExtension = ".xls"

---

So far so good. But when the file is displayed in excel, the gridline is not displayed.

How can I make the gridlines display when exporting to excel?

Many thanks.