.Binding checkbox error in windows vb.net

in vb.net visual studio 2013 windows forms

sample project picture

I notice when using in binding checkbox checked (slow and sometimes error at run time) while using "checkstate" works correctly Is there way to bind checkbox with checked and unchecked only without null without problems

Sample code include

Sub bindingTest(container As Control, sql As String, BindingSource1 As BindingSource, BindingNavigator1 As BindingNavigator)
    Dim field As String

    Dim str As String = ""
    da = New SqlDataAdapter(sql, CSql.sqlDatabaseConnString)
    ds = New DataSet()
    da.Fill(ds)
    BindingSource1.DataSource = ds.Tables(0)
    BindingNavigator1.BindingSource = BindingSource1
    For Each oc As Control In container.Controls
        If (TypeOf (oc) Is CheckBox) Then
            Dim oType As CheckBox
            oType = CType(oc, CheckBox)
            field = oType.Tag.ToString
            oc.DataBindings.Clear()
            If varcheckState = True Then
                '' working fine 
                oType.DataBindings.Add(New Windows.Forms.Binding("checkstate", BindingSource1, field, True))
            Else
                ''' slow and sometimes not working 
                oType.DataBindings.Add(New Windows.Forms.Binding("Checked", BindingSource1, field, False))
            End If
        End If


    Next
End Sub