access数据库已经连接成功，数据也可以显示在datagrid表里，但在textbox里输入新数据无法加入到现有的表里，只能修改第一行，求解！

源代码：
Imports System.Data
Imports System.Data.OleDb
Imports System.Data.SqlClient Public Class Form1
Dim MyBind As bindingmanagerbase
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: 这行代码将数据加载到表“ThermalDataSet.Thermal”中。您可以根据需要移动或删除它。
Me.ThermalTableAdapter.Fill(Me.ThermalDataSet.Thermal)
Dim strConn As String
strConn = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source =thermal.mdb"
Dim objConn As New OleDbConnection(strConn)
objConn.Open()
Dim strSql = "Select * From thermal"
Dim objAdap As New OleDbDataAdapter(strSql, objConn)
objConn.Close()
Dim objDSet As New DataSet
objAdap.Fill(objDSet, "thermal")
DataGridView1.DataSource = objDSet.Tables("thermal")
TextBox1.DataBindings.Add(New Binding("text", objDSet, "thermal.加热功率"))
TextBox2.DataBindings.Add(New Binding("text", objDSet, "thermal.测试电流"))
TextBox3.DataBindings.Add(New Binding("text", objDSet, "thermal.结温"))
TextBox4.DataBindings.Add(New Binding("text", objDSet, "thermal.壳温"))
MyBind = Me.BindingContext(objDSet, "thermal") End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim strConn As String = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source =thermal.mdb"
Dim objConn As New OleDbConnection(strConn)
Dim objAdap As New OleDbDataAdapter()
Dim objDSet As New DataSet()
objConn.open()
Dim heat As New OleDbParameter("@heat", OleDbType.Integer, 10)
Dim test As New OleDbParameter("@test", OleDbType.Integer, 10)
Dim jie As New OleDbParameter("@jie", OleDbType.Integer, 10)
Dim ke As New OleDbParameter("@ke", OleDbType.Integer, 10)
Dim strin As String = "Insert into thermal(加热功率，测试电流，结温，壳温）""values(@heat,@test,@jie,@ke)"
Dim objCmd As New OleDbCommand(strin, objConn)
objCmd.Parameters.Add(heat)
objCmd.Parameters.Add(test)
objCmd.Parameters.Add(jie)
objCmd.Parameters.Add(ke)
heat.Value = TextBox1.Text
test.Value = TextBox2.Text
jie.Value = TextBox3.Text
ke.Value = TextBox4.Text
MessageBox.Show(objCmd.ExecuteNonQuery())
objConn.Close()
Dim strsql = "select * from thermal"
objAdap.SelectCommand = New OleDbCommand(strsql, objConn)
objDSet.Clear()
objAdap.Fill(objDSet, "thermal")
End Sub
End Class