I've had this exact same problem before when I wrote a Java app to connect to Googles search results. Google blocks unauthorized connections and im assuming this site your trying to connect to is doing the same.

I got round this by using the setRequestProperty like you have.

Try changing it to:

Code:
urlConn.setRequestProperty( "User-Agent", "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0; H010818)" );