Проверка на ключ из реестра - C#

string s1 = reg.GetValue("JavaHome").ToString();

 private void button2_Click(object sender, EventArgs e)
        {
            string soft = "\\soft\\jdk7u3.exe";
            string dr;
            dr = Application.StartupPath;
            RegistryKey reg = Registry.LocalMachine.OpenSubKey ("Software\\JavaSoft\\Java_Development_Kit\\1.6.0_31\\");
            string s1 = reg.GetValue("JavaHome").ToString();
            if (reg != null)
            {
                MessageBox.Show("java +");
                
            }
            else
            {
                MessageBox.Show("Java -");
               System.Diagnostics.Process.Start(dr + soft);
            }
        }