[android help] android application not working with http://www.hostname.com

i've done an application in android which sends datas as parameters to remote mysql database using the following code with url as http://www.hostname.com.au/insert1.jsp as given below.

 HttpClient httpclient = new DefaultHttpClient();
 HttpPost httppost = new HttpPost("http://www.hostname.com.au/insert1.jsp");
 String trackid= getIntent().getExtras().getString("param1");
 :
 :

but the above url did'nt works in some android mobiles when i changed
http://www.hostname.com.au/insert1.jsp
to
http://hostname.com.au/insert1.jsp
it seems working .

can anyone please tell me what's the reason behind this.

.

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