[android help] success in logcat but empty screen

I currently have this one problem. and because of this, i cant do any other because i have to refer to this page. I would be grateful if anyone could point out the mistake i made.

I wanted to view the details of a specific product where the button from previous page (list) will pass the ID parameter to the page (details). there is no error in the Java code or PHP code. i'm sure about this because the Logcat shows the results accordingly (as i added the log thing everywhere). but the page is empty in the emulator. i don't understand why this happens as the layout is designed same as other pages as well. In case you need the code, its as below:

Java code: list.java

ListView lv = getListView();

    lv.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView parent, View view,
                int position, long id) {

            String pid = ((TextView) view.findViewById(R.id.pid)).getText()
                    .toString();

            // Starting new intent
            Intent in = new Intent(getApplicationContext(),
                    details.class);
            // sending pid to next activity
            in.putExtra(TAG_PID, pid);

            // starting new activity and expecting some response back
            startActivity(in);
        }
    });

Java code: details.java

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_book_details);


        Intent i = getIntent();

        // getting product id (pid) from intent
        pid = i.getStringExtra(TAG_PID);

        Log.d("pid is:",pid);

        new GetProductDetails().execute();

    }

 class GetProductDetails extends AsyncTask {


        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(Details.this);
            pDialog.setMessage("Loading. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        protected String doInBackground(String... params) {


            runOnUiThread(new Runnable() {
                public void run() {

                    int success;
                    try {
    List params = new ArrayList();
               params.add(new BasicNameValuePair("pid", pid));

JSONObject json = jParser.makeHttpRequest(url_product_details, "GET", params);


   Log.d("Single Product Details", json.toString());


                        success = json.getInt(TAG_SUCCESS);
                        if (success == 1) {

    JSONArray productObj = json.getJSONArray(TAG_BOOK);
JSONObject product = productObj.getJSONObject(0);                           
    title = product.getString(TAG_TITLE);
                        description=product.getString(TAG_CATEGORY);

Layout: details.xml

android:layout_width="match_parent"
android:layout_height="match_parent" >

    android:layout_marginTop="70dp"
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_marginLeft="20dp"/>

thank you so much!

.

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