حاول تستخدم هذا الكود
كود :
Private Sub redpepole()
On Error Resume Next
Dim ss As Integer
For i = 0 To DataGridView1.Rows.Count - 1
ss = DataGridView1.Rows(i).Cells("Exp").Value.ToString
If ss = "null" Then
DataGridView1.Rows(i).DefaultCellStyle.BackColor = Color.Red
Else
End If
Next
End Sub