Sketch upload error

gistfile1.txt

	public void upload(View view) {
		try {
			final class completionCallback implements Callback<PositionedSketch> {
				Activity a;
				public completionCallback(Activity object) {
					a = object;
				}
				
				public void onCallback(PositionedSketch data) {
					if(data != null) {
						// TODO: go back to home screen?
						Toast.makeText(getApplicationContext(),
								"Successfully Uploaded the Graffiti!", Toast.LENGTH_SHORT)
								.show();
						goHome();
					}
					else {
						// TODO: toast
						Log.e("upload", "Failed to upload graffiti");
					}
					
					// TODO: hide progressbar
				}
			}
			
			// TODO: show progressbar
			ToggleButton permission = (ToggleButton)findViewById(R.id.permissions);	
			PositionedSketch.Permission p = permission.isChecked() ? PositionedSketch.Permission.Private : PositionedSketch.Permission.Public;
			ps.setPermissions(p);
			ps.setLatitude(lat);
			ps.setLongitude(lng);
			GraffitiCom.storePositionedSketch(ps, new completionCallback(this));
		} catch(Exception e) {
			e.printStackTrace();
		}

Stack trace

11-30 21:19:51.034: E/AndroidRuntime(1538): FATAL EXCEPTION: AsyncTask #2
11-30 21:19:51.034: E/AndroidRuntime(1538): java.lang.RuntimeException: An error occured while executing doInBackground()
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at android.os.AsyncTask$3.done(AsyncTask.java:200)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.FutureTask.run(FutureTask.java:137)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.lang.Thread.run(Thread.java:1096)
11-30 21:19:51.034: E/AndroidRuntime(1538): Caused by: java.lang.ClassCastException: [Ljava.lang.Object;
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at srl.graffiti.client.nio.GraffitiClient$3.doInBackground(GraffitiClient.java:1)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at android.os.AsyncTask$2.call(AsyncTask.java:185)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
11-30 21:19:51.034: E/AndroidRuntime(1538): 	... 4 more