求助:无法打开备份设备 'C:\Documents and Settings\Administrator\桌面\Check'。出现操作系统错误 5(拒绝访问。)

private void btnGo_Click(object sender, EventArgs e)
{
this.txtFile.Text = this.folderBrowserDialog1.SelectedPath.ToString().Trim();
string saveAway = this.txtFile.Text;
string cmdText = @"backup database ERP_DB to disk='" + saveAway + "'";
BakReductSql(cmdText, true);

}

private void BakReductSql(string cmdText, bool isBak)
{
SqlCommand cmdBakRst = new SqlCommand();
SqlConnection conn = new SqlConnection("Data Source=WANGKAI;Initial Catalog=ERP_DB;uid=sa;pwd=sasa;");
try
{
conn.Open();
cmdBakRst.Connection = conn;
cmdBakRst.CommandType = CommandType.Text;

cmdBakRst.CommandText = cmdText;
cmdBakRst.ExecuteNonQuery();
MessageBox.Show("恭喜，你已经成功备份当前数据！", "系统消息");

}
catch (Exception ex)
{

MessageBox.Show("对不起，操作失败", "系统消息");
}
finally
{
cmdBakRst.Dispose();
conn.Close();
conn.Dispose();
}
}

昨天一下午解决这个问题..始终找不到原因,还是请各位兄弟帮个忙,麻烦指点下吧