How to check for the same values ​​in DataGridView1.Rows(i).Cells(2) with items in combobox?

Question

Visual Basic

Good afternoon. The problem is this, I write a schedule for receiving patients, it is necessary that the items in the combobox be enabled, temporarily, if they already exist in the table. Nothing works.
For i As Integer = 0 To DataGridView1.RowCount - 2
If DataGridView1.Rows(i).Cells(2). ToString= ComboBox4.SelectedItem Then
MsgBox("This time is already taken!", MsgBoxStyle.Information)// Instead of this message, it is necessary that the item became enabled
End If
Next

Answer 1

It is impossible to make separate items as enabled in a combobox.