NullPointerException when trying to open database

I'm trying to include an item in the DB that was selected, but when I try to open the database using .open(); I'm getting a NullPointerException error.

public class CadPreVenda extends ListActivity{

private static final String[] FORMASDEPAGAMENTO = new String[]{"À VISTA - DINHEIRO","À VISTA - CHEQUE","À VISTA - CARTAO","À PRAZO - CARTAO","À PRAZO - CHEQUE","À PRAZO - CREDIARIO","À PRAZO - BOLETO BC"}; 

List<LCZ002> itensPV;
ItemPreVendaAdapter adapter;
ItemPreVendaDAO itemPVDAO;

// I removed a part of the code that has no connection to the problem.

public void onActivityResult(int requestCode, int resultCode, Intent it) {

        Intent itquant = new Intent(CadPreVenda.this, pvItemQuantidade.class);
        if(it == null){
            Log.d("ERRO", "Algum erro encontrado"); 
        }
        else if (requestCode == 1){ 

            Bundle params = it !=null ? it.getExtras(): null;

            if (params != null ){
                final LCM001 produto = (LCM001) params.get("produto");
                if(requestCode == 0){
                    Toast.makeText(getApplicationContext(), "RequestCode = 0. Erro.", Toast.LENGTH_SHORT).show();
                }
                else{
                    new AlertDialog.Builder(this).setTitle("Produto: "+produto.getDescricao())
                    .setIcon(R.drawable.lupa)
                    .setMessage("Valor do produto: R$"+ produto.getVrVenda()+"\nConfirma inclusão do produto?")

                    .setNegativeButton("Não", new OnClickListener(){
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            finish();
                        }//fim onClick
                    }) //fim onClickListener_NegativeButton

                    .setPositiveButton("Sim", new OnClickListener(){
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            int numPV=1;
                            int codItem= (int) produto.getId();
                            double valorItem = Double.parseDouble(produto.getVrVenda());
                            double quantidadeItem= 1;
                            String descricao = produto.getDescricao();
                            String unidade = produto.getUnidade();

                            LCZ002 itemPV = new LCZ002(numPV, codItem, valorItem, quantidadeItem, descricao, unidade);
                            itemPVDAO.open();// <<<<<< Aqui ocorre o erro.
                            itemPVDAO.novoItemPV(itemPV);
                            itemPVDAO.close();
                            //Fim Salva Item PV

                        }//fim onclick
                    })      /*fim onCLickListener*/
                    .show();
                }

            } //if (params != null )
        }//

LogCat:

06-17 10:00:44.614: E/AndroidRuntime(1300): FATAL EXCEPTION: main
06-17 10:00:44.614: E/AndroidRuntime(1300): Process: br.sysandroid, PID: 1300
06-17 10:00:44.614: E/AndroidRuntime(1300): java.lang.NullPointerException
06-17 10:00:44.614: E/AndroidRuntime(1300):     at br.sysandroid.CadPreVenda$3.onClick(CadPreVenda.java:179)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at android.os.Handler.dispatchMessage(Handler.java:102)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at android.os.Looper.loop(Looper.java:136)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at android.app.ActivityThread.main(ActivityThread.java:5017)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at java.lang.reflect.Method.invokeNative(Native Method)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at java.lang.reflect.Method.invoke(Method.java:515)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
06-17 10:00:44.614: E/AndroidRuntime(1300):     at dalvik.system.NativeStart.main(Native Method)

ItemPreVendaDAO Class

package br.sysandroid.dao;

import java.util.ArrayList;
import java.util.List;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import br.sysandroid.dao.banco.BancoDAO;
import br.sysandroid.dao.banco.Lcz002DAO;
import br.sysandroid.model.LCZ002;

public class ItemPreVendaDAO {

    private SQLiteDatabase database;
    private BancoDAO bancoDAO;

    public ItemPreVendaDAO(Context context) {
        bancoDAO = new BancoDAO(context);
    }

    public void open() throws SQLException {
        database = bancoDAO.getWritableDatabase();
    }

    public void close() {
        bancoDAO.close();
    }


        public long novoItemPV(LCZ002 itemPV) {
            ContentValues values = new ContentValues();

            values.put(Lcz002DAO.CAMPO_NUM_PREVENDA, itemPV.getNumPV());
            values.put(Lcz002DAO.CAMPO_CODIGO_PRODUTO_ITENS, itemPV.getCodigoItemPV());
            values.put(Lcz002DAO.CAMPO_VALOR_UNITARIO_ITEM_PREVENDA, itemPV.getValorUnitarioPV());
            values.put(Lcz002DAO.CAMPO_QUANTIDADE_VENDIDA_ITEM_PREVENDA, itemPV.getQuantidadeItemPV());
            values.put(Lcz002DAO.CAMPO_DESCRICAO_ITEM_PREVENDA, itemPV.getDescricaoItemPV());
            values.put(Lcz002DAO.CAMPO_UNIDADE_ITEM_PREVENDA, itemPV.getUnidadeItemPV());
            return database.insert(Lcz002DAO.TABELA_PREVENDA_ITENS, null, values);

        }
}