Excel单元格使用C＃进行合并时隐藏Windows对话框

I am exporting gridview to Excel in windows application successfully, but the problem is when I am going to Merge some range of cells in that excel sheet, it raises a windows dialogue box. So each and every time I am merging those cells it does not give any exception but it's showing a dialogue box. I am exporting gridview to Excel in windows app