DataGridViewComboBoxColumn not displaying data as expected

DataGridViewComboBoxColumn comboboxColumn = new DataGridViewComboBoxColumn();
			comboboxColumn.DataPropertyName = "PRIORITY";
			comboboxColumn.HeaderText = "Priority";
			comboboxColumn.Name = "PRIORITY";
			comboboxColumn.DropDownWidth = 90;
			comboboxColumn.Width = 100;
			comboboxColumn.MaxDropDownItems = 3;
			comboboxColumn.FlatStyle = FlatStyle.Flat;
			comboboxColumn.SortMode = DataGridViewColumnSortMode.Automatic;
			string[] priorityData = new string[2];
			for (int i = 1; i <= 3; i++)
			{
				priorityData[0] = i.ToString();
				switch (i)
				{
					case 1:
						priorityData[1] = "High";
						break;
					case 2:
						priorityData[1] = "Medium";
						break;
					case 3:
						priorityData[1] = "Low";
						break;
					default:
						break;
				}
				ListViewItem itm = new ListViewItem(priorityData);
				itm.Selected = false;
				comboboxColumn.Items.Add(itm);
			}
			comboboxColumn.ValueMember = "Key";
			comboboxColumn.DisplayMember = "Value";
			dgvSoNInvestment.Columns.Add(comboboxColumn);