datagrid数据导入Excel出错,请高手帮忙,好急呀!!!!!!!

protected void wriyrDataGridToExcel()

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{

bool popConfirm = true;

Microsoft.Office.Interop.Owc11.SpreadsheetClass xlsheet = new Microsoft.Office.Interop.Owc11.SpreadsheetClass();

int i = 0;

int j = 0;

int numbercols;

//输出标题

DataGridColumn oItem;

for (i = 0; i < this.dg.Columns.Count; i++)

{

oItem = this.dg.Columns[i];

xlsheet.ActiveSheet.Cells[1, i + 1] = oItem.HeaderText;

}

if (dg.Items.Count != 0)

numbercols = dg.Items[0].Cells.Count;

else numbercols = 0;

//输出字段内容

for (j = 0; j < dg.Items.Count; j++)

{

for (i = 0; i < numbercols; i++)

{

xlsheet.get_Range(xlsheet.Cells[2,1], xlsheet.Cells[j+2,i+1]).AutoFit();