How to track the check box of the data grid view

Dim Y As DataGridViewCheckBoxCell
Dim Count As Decimal = 0
For Each DGVRow As DataGridViewRow In DataGridView1.Rows
Y = CType(DGVRow.Cells("Chk"), DataGridViewCheckBoxCell)
If Y.Value = True Then
Count = Count + 1
End If
Next
MsgBox(Count & " items checked.")