分页的问题

DataSet ds=new DataSet();
string sql = "select * from ST_PPTN_R";
DataTable dt1 = ClsSql.getTable(sql);//自己写的函数，执行sql,返回DataTable
int recordCount = dt1.Rows.Count;//分页记录总数
DataTable table = new DataTable();
for (int i = (currentPageIndex - 1) * pageSize; i < currentPageIndex * pageSize; i++)
{
  table.Rows.Add(dt1.Rows[i]);
}
ds.Tables.Add(table);

return ds;
为什么老是错啊，说dt1.Rows[0]没有数据