How to Update a SQL table with data from a DataSet

I am pulling data from 1 database(QAD) into a DataSet. I need help trying to Update a table in a different database(Inventory_Test) with the data collected in the DataSet.
Here is how i pull in the data from the databases to the DataSets:

Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.DataRelation

Public Class Form1
    Private QAD As SqlDataAdapter
    Private Inventory_Test As SqlDataAdapter
    Private QADStatus As DataSet


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim connectionString As String

        connectionString = "My connection to QAD Database"

        Dim objConn As New SqlConnection(connectionString)
        objConn.Open()
        Dim sqlString As String
        sqlString = ""
        sqlString = "SELECT PT_Part, PT_STATUS, PT_DRWG_SIZE FROM PT_MSTR"

        QAD = New SqlDataAdapter(sqlString, objConn)

        connectionString = ""
        connectionString = "My Connection to Inventory_Test Database"
        objConn = New SqlConnection(connectionString)
        objConn.Open()
        sqlString = ""
        sqlString = "SELECT Inventory_Number, Status, drwg_size FROM Inventory_Test"

        Inventory_Test = New SqlDataAdapter(sqlString, objConn)

        QADStatus = New DataSet
        QAD.Fill(QADStatus, "QAD")
        Inventory_Test.Fill(QADStatus, "Inventory_Test")

        
        Dim QADtable As DataColumn
        Dim InvenTable As DataColumn
        Dim data_relation As DataRelation

        QADtable = QADStatus.Tables("QAD").Columns("PT_Part")
        InvenTable = QADStatus.Tables("Inventory_Test").Columns("Inventory_Number")
        data_relation = New DataRelation("QADtoInventory_Test", QADtable, InvenTable)
        QADStatus.Relations.Add(data_relation)

        DataGridView1.DataSource = QADStatus
   End Sub

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Inventory_Test.Update(QADStatus, "Inventory_Test")
        MsgBox("SQL Server DB was updated " & Chr(13) & "Check Server Explorer to see changes")
    End Sub

When i run this, nothing happens. Any ideas??