Please help i am a newbie on oracle database i am used on using mysql and i really don't have any idea how can i debug my code. Here is my code.

```
Imports System.Diagnostics
Imports Oracle.DataAccess.Client
Imports Oracle.DataAccess.Types

Public Class mainMenu

Dim conn As New OracleConnection
Private cmd As OracleCommand
Private da As OracleDataAdapter
Private cb As OracleCommandBuilder
Private ds As DataSet
Private Sub mainMenu_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    AddHandler txtProductName.TextChanged, AddressOf ValidateInputs
    AddHandler txtQty.TextChanged, AddressOf ValidateInputs
    AddHandler txtPrice.TextChanged, AddressOf ValidateInputs
    conn.ConnectionString = "User Id=antonina" & _
    ";Password=antonina" & _
    ";Data Source=xe"
    Try
        conn.Open()
    Catch ex As Exception
        MessageBox.Show(ex.Message.ToString())
    Finally
        conn.Dispose()
    End Try
End Sub
Private Sub ValidateInputs(ByVal Sender As Object, ByVal e As EventArgs)
    Button1.Enabled = Not (txtProductName.Text = String.Empty OrElse txtQty.Text = String.Empty OrElse txtPrice.Text = String.Empty)
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
    Dim productName As String
    Dim qty As Integer
    Dim price As Integer
    Dim cat As String
    productName = txtProductName.Text
    qty = Integer.Parse(txtQty.Text)
    price = Integer.Parse(txtPrice.Text)
    cat = cmbCat.Text
    conn = New OracleConnection("User Id=antonina;Password=antonina;Data Source=xe")
    da = New OracleDataAdapter()
    Try
        da.InsertCommand = New OracleCommand("INSERT INTO INVENTORY(INVENTORY_PRODUCTNAME,INVENTORY_CAT,INVENTORY_QTY,INVENTORY_PRICE) VALUES ('" & productName & "'," & qty & "," & price & ",'" & cat & "')", conn)
        Debug.WriteLine("Success")
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try

End Sub
End Class

```

When i click my `add` button it says object reference not set to an instance of an object. I know i might just have a stupid syntax error. Please help me.

I am sure that all my variables have a value. also i am using oracle 10g