如何将datagridview视图的值放到listview c＃

I have a DataGridView store data from DataTable get from SQL database. This step is nothing error. But when I try to get all data in DataGridView into ListView, it always say that: "Additional information: Object reference not set to an instance of an object." when running to code line add data to listview.I have a DataGridView store data from DataTable