急：8004005:缺少更新或刷新的键列信息

Private Sub CmdDeal_Click()
    If rs.RecordCount > 0 Then
        msg = MsgBox("您确实要还书吗?", vbYesNo)
        If msg = vbYes Then
            rs.Fields("dateBack") = Format(Now, "yyyy-mm-dd") '更新借还信息的"还书日期"
            rs.Update                        '更新数据
            '图书的存储数量加1
            SQL = " update 图书信息表 set volume=volume+1 where bookID='"
            SQL = SQL & Trim(Me.txtBookNo.Text) & "'"
            Call ExecuteSQL(SQL, msg)
            
            If CDbl(Me.LblPenalty.Caption) > 0 Then
                MsgBox ("还书成功，" & "罚款金额为：" & Me.LblPenalty.Caption)
                '将罚款金额添加到读者信息表中
                SQL = "update 读者信息表 set fineR=fineR+" & CDbl(Me.LblPenalty.Caption)
                SQL = SQL & " where readerID = '" & Trim(txtQuery.Text) & "'"
                Call ExecuteSQL(SQL, msg)
            Else
                MsgBox ("还书成功!")
            End If
            Call LoadData                    '装载数据
            Call ShowData                    '显示数据
        Else
            Exit Sub
        End If
    Else
        MsgBox ("没有可以处理的续借信息")
    End If
End Sub

我这段代码到底是哪里出现问题了
          rs.Update                        '更新数据
这句出现这个错误
紧急求助，毕设临近啊~~~~

这是数据库的调用~高手帮个忙好吗
Private Sub LoadData()
'装载数据
    '得到查询条件
    Set rs = Nothing
    '查询图书信息,构建SQL语句
    SQL = "SELECT a.bookID,b.title,b.author,b.publishTime,a.dateBorrow,a.dateBorrow2,a.dateBack "
    SQL = SQL & " FROM 借还信息表 a INNER JOIN  图书信息表 b ON a.bookID = b.bookID "
    SQL = SQL & " WHERE (a.dateBack IS NULL)  AND (a.readerID = '"
    SQL = SQL & Trim(txtQuery.Text) & "')"
    Set rs = SelectSQL(SQL, msg)
    Set Me.DataGrid1.DataSource = rs
    DataGrid1.Refresh
End Sub