ارورری عجیب

من بار اول که برنامه رو اجرا میکنم با این ارور روبرو میشم. ولی دومین بار که اجرا میکن صحیح و سالم اجرا میشه !؟ این ارورر واسه چی میتونه باشه ؟

08-14 16:28:20.441: W/System.err(2358): org.json.JSONException: End of input at character 1 of  
08-14 16:28:20.441: W/System.err(2358): 	at org.json.JSONTokener.syntaxError(JSONTokener.java:450)
08-14 16:28:20.441: W/System.err(2358): 	at org.json.JSONTokener.nextValue(JSONTokener.java:97)
08-14 16:28:20.441: W/System.err(2358): 	at org.json.JSONArray.<init>(JSONArray.java:87)
08-14 16:28:20.441: W/System.err(2358): 	at org.json.JSONArray.<init>(JSONArray.java:103)
08-14 16:28:20.441: W/System.err(2358): 	at serialdbproject.ActivitySerials.populateFromServer(ActivitySerials.java:275)
08-14 16:28:20.441: W/System.err(2358): 	at serialdbproject.ActivitySerials.access$0(ActivitySerials.java:266)
08-14 16:28:20.441: W/System.err(2358): 	at serialdbproject.ActivitySerials$LoadingTask.doInBackground(ActivitySerials.java:222)
08-14 16:28:20.441: W/System.err(2358): 	at serialdbproject.ActivitySerials$LoadingTask.doInBackground(ActivitySerials.java:1)
08-14 16:28:20.441: W/System.err(2358): 	at android.os.AsyncTask$2.call(AsyncTask.java:287)
08-14 16:28:20.441: W/System.err(2358): 	at java.util.concurrent.FutureTask.run(FutureTask.java:234)
08-14 16:28:20.441: W/System.err(2358): 	at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
08-14 16:28:20.441: W/System.err(2358): 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
08-14 16:28:20.441: W/System.err(2358): 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
08-14 16:28:20.441: W/System.err(2358): 	at java.lang.Thread.run(Thread.java:856)