求助:关于获取路径问题

是这样的,在form窗体上有两个按钮,一个为btnImpor "导入Excel",另一个为btnExpor "导出Excel"
要求点击btnImpor时,会弹出openfiledialog对话框，获取用户选择的文件路径
点击btnExpor时，会弹出savefiledialog对话框，获取用户选择的路径和文件名
我的代码btnImpor调用方法时报错，btnExpor不写方法调用也报错，求解。

public string OpenFileDialogGetPath()
        {
            string path = "";
            using (OpenFileDialog ofd = new OpenFileDialog())
            {
                ofd.InitialDirectory = "c:\\";
                ofd.Filter = "Excel文档(*.xls)|*.xls";
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    path = ofd.FileName;
                }
            }
            return path;
        }

 string path = "";
            SaveFileDialog sf = new SaveFileDialog();
            sf.InitialDirectory = "d:\\";
            sf.Filter = "Excel文档|*.xls";
            if (sf.ShowDialog() == DialogResult.OK)
            {
                path = sf.FileName;
            }
            MessageBox.Show(path);