sql server compact在wpf中的应用问题

[aidwen_chen]

刚接触sql server compact，不会用，在网上找了资料写了下面程序，编译执行都没提示错误，但插入数据却怎么也行不通，求大侠指教呀！！！
运行环境：vs2010wpf中；用到的数据库：sql server compact4.0
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data.Entity;
using System.Data.SqlServerCe;


namespace WpfApplication6
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
///

public partial class MainWindow : Window
{

public MainWindow()
{
InitializeComponent();
//更新数据库，因为用的vs2010旗舰版自带的compact3.5，而组件中配置环境给的4.0，所以更新了
string connStringCI = "Data Source= Database1.sdf; LCID= 1033";
SqlCeEngine engine = new SqlCeEngine(connStringCI);
engine.Upgrade(connStringCI);
}

private void button1_Click(object sender, RoutedEventArgs e)
{
SqlCeConnection conn = null;
conn = new SqlCeConnection("Data Source = Database1.sdf;Password =");
SqlCeCommand cmd = conn.CreateCommand();
cmd.CommandText = @"INSERT INTO test1 (password,username) VALUES ('1234','aidwen')";
conn.Open();
//测试部分，该段代码可以实现数据读取但上面的代码插入数据就实现不了
//cmd.CommandText = @"select * from test1";
SqlCeDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
{
int val1 = rdr.GetInt32(0);
string val2 = rdr.GetString(1);
string val3 = rdr.GetString(2);
MessageBox.Show(val1.ToString() + '|' + val2 + '|' + val3);
}
cmd.ExecuteNonQuery();
MessageBox.Show(cmd.CommandText.ToString() + '|' + cmd.ExecuteNonQuery().ToString());

}
}
}