Textbox lookup through ComboBox

[CodeJoker]

Hey I am trying to create a textbox that relays text to my combobox on my for so I may lookup details in my DB but I get two errors . . .First there is a Primary Key error, "Table does not have a primary key" and if I do it the other way around by asking my textbox alone to lookup my values that I put in I seem to receive the same values regardless of what I put in my texbox. . . Please review these different codes and see if anyone can spot my mistake. . . Replies would be greatly appreciated.

TEXTBOX LOOKUP CODE:

Private m_cnADONetConnection As New OleDb.OleDbConnection()
Private m_daDataAdapter As OleDb.OleDbDataAdapter
Private m_cbCommandBuilder As OleDb.OleDbCommandBuilder
Private m_dtCD As New DataTable
Dim m_rowPosition As Integer = 0

Private Sub StockDetailsForm_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
   m_cnADONetConnection.ConnectionString = _
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\TEST.mdb"

   m_cnADONetConnection.Open()

   m_daDataAdapter = New OleDb.OleDbDataAdapter("Select * From CD", m_cnADONetConnection)
   m_cbCommandBuilder = New OleDb.OleDbCommandBuilder(m_daDataAdapter)
   m_daDataAdapter.Fill(m_dtCD)


Public Sub StockCheck()

StockEdit_Open_Conn()
Dim sql = "SELECT CouplingCode ,AlbumTitle ,ReleaseDate ,TotalSongs ,PPD FROM CD WHERE CouplingCode='" & StockDetailsForm.txtSearch.Text & "'"
Dim cmd As New System.Data.OleDb.OleDbCommand

cmd = New OleDbCommand(sql, m_cnADONetConnection)
Dim exReader As OleDbDataReader = cmd.ExecuteReader
m_cbCommandBuilder = New OleDb.OleDbCommandBuilder(m_daDataAdapter)


Private Sub txtSearch_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.Leave

Try
If exReader.Read = False Then
MessageBox.Show("Stock Item does not exist", "Stock Item Error", MessageBoxButtons.OK, MessageBoxIcon.Stop)
m_cnADONetConnection.Close()
m_cnADONetConnection.Dispose()
Else
StockDetailsForm.CouplingCodeID.Text = _
m_dtCD.Rows(m_rowPosition)("CouplingCode").ToString()
StockDetailsForm.txtAlbumName.Text = _
m_dtCD.Rows(m_rowPosition)("AlbumTitle").ToString()
StockDetailsForm.txtPPD.Text = _
m_dtCD.Rows(m_rowPosition)("PPD").ToString()
StockDetailsForm.txtTotalSongs.Text = _
m_dtCD.Rows(m_rowPosition)("TotalSongs").ToString()
StockDetailsForm.dtpReleaseDate.Text = _
m_dtCD.Rows(m_rowPosition)("ReleaseDate").ToString()
StockDetailsForm.txtQtyHand.Text = _
m_dtCD.Rows(m_rowPosition)("QtyOnHand").ToString()
End If
End Sub

TEXTBOX TO COMBOBOX LOOKUP CODE :

    Private m_cnADONetConnection As New OleDb.OleDbConnection
    Private m_daDataAdapter As OleDb.OleDbDataAdapter
    Private m_cbCommandBuilder As OleDb.OleDbCommandBuilder
    Private m_dtCD As New DataTable
    Dim m_rowPosition As Integer = 0

    Private Sub NewEditCDForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        m_cnADONetConnection.ConnectionString = _
        "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\TEST.mdb"

        m_daDataAdapter = New OleDb.OleDbDataAdapter("Select * From CD", m_cnADONetConnection)
        m_cbCommandBuilder = New OleDb.OleDbCommandBuilder(m_daDataAdapter)
        m_daDataAdapter.Fill(m_dtCD)

        m_cnADONetConnection.Open()
    End Sub

    Private Sub txtSearch_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.Leave
        Try
            CDLookup.Text = txtSearch.Text
            CDLookup.Text = _
            m_dtCD.Rows.Find("CouplingCode").ToString()

            Dim sql = "SELECT * FROM CD WHERE CouplingCode='" & txtSearch.Text & "'"
            Dim cmd As New System.Data.OleDb.OleDbCommand
            cmd = New OleDbCommand(sql, m_cnADONetConnection)
            Dim exReader As OleDbDataReader = cmd.ExecuteReader


            If exReader.Read = False Then

                MessageBox.Show("Invalid Username and/or Password. . . ", "Authentication Has Faild", MessageBoxButtons.OK, MessageBoxIcon.Stop)

            Else
                CouplingCodeID.Text = _
                m_dtCD.Rows.Find(m_rowPosition)("CouplingCode").ToString()
                Exit Sub
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

[mzmishra]

Did you try to debug and see what value you are getting as textbox text.I think it is somehow set to some default or initial value