DataGridViewComboBox value is not valid linq

Question

Im filling my datagridview comboxcolumn with this code:

 (dgvHopDong.Columns["MaNCC"] as DataGridViewComboBoxColumn).DataSource = QL.NhaCungCaps.Select(n => new { MaNCC = n.MaNCC, TenNCC = n.TenNCC }).ToList();            
            (dgvHopDong.Columns["MaNCC"] as DataGridViewComboBoxColumn).DisplayMember = "TenNCC";
            (dgvHopDong.Columns["MaNCC"] as DataGridViewComboBoxColumn).ValueMember = "MaNCC";

and the error is:

DataGridViewComboBoxCell value is not valid?

and i dont know why. thank you so much!

Answer 1

值类型缺失。

(dgvHopDong.Columns["MaNCC"] as DataGridViewComboBoxColumn).ValueType = typeof(string);