I want try this sub from 

http://forums.infragistics.com/forums/t/19898.aspx 

protected void ExportToExcel(object sender, EventArgs e)
    {
        Infragistics.Excel.Workbook workbook = new Infragistics.Excel.Workbook();
        workbook.Worksheets.Add("Sheet1");
        workbook.Worksheets.Add("Sheet2");

        this.CopyPasteGrid1.DisplayLayout.ColHeadersVisibleDefault = ShowMarginInfo.No;
        this.UltraWebGridExcelExporter1.Export(this.CopyPasteGrid1, workbook);
        for (int i = 0; i < this.CopyPasteGrid1.Columns.Count; i++)
        {
            workbook.Worksheets[0].Columns[i].Width = 2000;
        }

        this.CopyPasteGrid2.DisplayLayout.ColHeadersVisibleDefault = ShowMarginInfo.No;
        workbook.ActiveWorksheet = workbook.Worksheets[1];
        this.UltraWebGridExcelExporter1.Export(this.CopyPasteGrid2, workbook);
        for (int i = 0; i < this.CopyPasteGrid2.Columns.Count; i++)
        {
            workbook.Worksheets[1].Columns[i].Width = 2000;
        }
        workbook.ActiveWorksheet = workbook.Worksheets[0];

    }

in VB.NET ..

but i have an error in :

Dim workbook As New Infragistics.Excel.Workbook

error says:

Workbook' is ambiguous in the namespace 'Infragistics.Excel' .

My Version:

<%@ Register assembly="Infragistics35.WebUI.UltraWebGrid.ExcelExport.v10.2, Version=10.2.20102.1011, Culture=neutral, PublicKeyToken=7dd5c3163f2cd0cb" namespace="Infragistics.WebUI.UltraWebGrid.ExcelExport" tagprefix="igtblexp" %>