title: how to force user to select drop down list item first before continue next in C#
body: <p><a href="http://www.tgv.com.my/" rel="nofollow">http://www.tgv.com.my/</a></p>
  
  <p>for example of this website, the quick ticket session.
  i need to force users to select a movie first before select the Cinema</p>