c# - DataGridViewComboBox value is not valid linq -

im filling datagridview comboxcolumn code:

 (dgvhopdong.columns["mancc"] datagridviewcomboboxcolumn).datasource = ql.nhacungcaps.select(n => new { mancc = n.mancc, tenncc = n.tenncc }).tolist();                         (dgvhopdong.columns["mancc"] datagridviewcomboboxcolumn).displaymember = "tenncc";             (dgvhopdong.columns["mancc"] datagridviewcomboboxcolumn).valuemember = "mancc"; 

and error is:

datagridviewcomboboxcell value not valid?

and dont know why. thank much!

the value type missing.

(dgvhopdong.columns["mancc"] datagridviewcomboboxcolumn).valuetype = typeof(string);