问让CheckBox.Checked在ASPxGridView中不正常工作

EN

<dxwgv:ASPxGridView ID="Grid_Loading_Plan_Detail" runat="server" >          
...
<dxwgv:GridViewDataColumn Caption="#" VisibleIndex="1">
<DataItemTemplate>
<dxe:ASPxCheckBox ID="loadingStatus" runat="server" Checked='<%# GetChecked(Eval("loadingStatus").ToString()) %>'></dxe:ASPxCheckBox>
</DataItemTemplate>
</dxwgv:GridViewDataColumn>
...
</dxwgv:ASPxGridView>

Public Function GetChecked(value As String) As Boolean
    Select Case value
        Case "1"
            Return True
        Case "0"
            Return False
        Case Else
            Return False
    End Select
End Function

Protected Sub btSimpan_Click(sender As Object, e As EventArgs) Handles btSimpan.Click
    Try
        sqlstring = ""
        For i As Integer = 0 To Grid_Loading_Plan_Detail.VisibleRowCount - 1
            Dim loadingStatus As DevExpress.Web.ASPxEditors.ASPxCheckBox = Grid_Loading_Plan_Detail.FindRowCellTemplateControl(i, Grid_Loading_Plan_Detail.Columns(1), "loadingStatus")

            sqlstring = sqlstring & " UPDATE containerTransaction SET loadingStatus = '" & IIf(loadingStatus.Checked, "1", "0") & "' " & _
                        " WHERE ID = '" & Grid_Loading_Plan_Detail.GetRowValues(i, "ID") & "'; "
        Next

        If SQLExecuteNonQuery(sqlstring) > 0 Then
            Response.Redirect("loading-plan.aspx")
        End If
    Catch ex As Exception
        Response.Write("Error btSimpan_Click <BR> " & ex.ToString)
    End Try
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Try
        If Not Page.IsPostBack Then
            Call Load_menu()
        End If
    Catch ex As Exception
        Response.Write("Page_Load Exception :<br>" & ex.ToString)
    End Try

    If Not Session("Grid_Loading_Plan_Detail") Is Nothing Then
        Grid_Loading_Plan_Detail.DataSource = CType(Session("Grid_Loading_Plan_Detail"), DataTable)
        Grid_Loading_Plan_Detail.DataBind()
    End If
End Sub

Private Sub Load_menu()
    Try
        sqlstring = "SELECT ID, code, date, container, seal, sender, receiver, [weight], loadingStatus " & _
            "FROM containerTransaction " & _
            "WHERE loadingCode = (SELECT TOP 1 code FROM loadingPlan WHERE ID = '" & ID & "') AND [status] = 1 " & _
            "ORDER BY [weight] "
        DS = SQLExecuteQuery(sqlstring)
        DT = DS.Tables(0)
        Session("Grid_Loading_Plan_Detail") = DT
        Grid_Loading_Plan_Detail.DataSource = DT
        Grid_Loading_Plan_Detail.KeyFieldName = "ID"
        Grid_Loading_Plan_Detail.DataBind()
    Catch ex As Exception
        Response.Write("Load_Menu Exception :<br>" & ex.ToString)
    End Try
End Sub