มีปัญหาในการ where โดยอ้างอิงจาก id ของตารางอื่น ครับ (VB)

Option Explicit On
Option Strict On

Public Class frm_care
    Dim dbDokmai As New dbdokmaiDataContext()
    Dim dt As db_dokmaiDataSet.customerDataTable
    Dim da As db_dokmaiDataSetTableAdapters.customerTableAdapter

    Dim dt_care As db_dokmaiDataSet.careDataTable
    Dim da_care As db_dokmaiDataSetTableAdapters.careTableAdapter

    Private Sub frm_care_Load(sender As Object, e As EventArgs) Handles MyBase.Load
     
        da = New db_dokmaiDataSetTableAdapters.customerTableAdapter()
        dt = New db_dokmaiDataSet.customerDataTable()

        da_care = New db_dokmaiDataSetTableAdapters.careTableAdapter()
        dt_care = New db_dokmaiDataSet.careDataTable()
        ShowCustomers()
        FormatDgv_customers()
   
    End Sub