Google in-app getprice() item problem ?

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Android

Google

I used the google sample Trivialdrive and I published the beta test. And I can buy my item, no problem. But I am trying to getPrice() a item and always "No found". Can you help me please. Thanks.

------- in IabHelper.class ------

public String getPricesDev(String packageName) throws RemoteException, JSONException{

    final String PACKAGE_NAME = mContext.getPackageName();

    ArrayList<String> skuList = new ArrayList<String>();
    skuList.add("infinite_gas_monthly");
    skuList.add("gas");
    skuList.add("infinite_gas");
    skuList.add("premium");
    Bundle querySkus = new Bundle();
    querySkus.putStringArrayList("ITEM_ID_LIST", skuList);

    Bundle skuDetails = mService.getSkuDetails(3,PACKAGE_NAME, "inapp", querySkus);

    int response = skuDetails.getInt("RESPONSE_CODE");
    if (response > 0) {
        ArrayList<String> responseList
                = skuDetails.getStringArrayList("DETAILS_LIST");

        for (String thisResponse : responseList) {
            JSONObject object = new JSONObject(thisResponse);
            String sku = object.getString("productId");
            String price = object.getString("price");
          if(sku.equals("infinite_gas_monthly")) return price;
        }
    }
    return "Not found";
}

------ in Mainactivity.class ----

IabHelper.QueryInventoryFinishedListener mGotInventoryListener = new IabHelper.QueryInventoryFinishedListener() {
    public void onQueryInventoryFinished(IabResult result, Inventory inventory) {
        // Have we been disposed of in the meantime? If so, quit.
        if (mHelper == null) return;
        // Is it a failure?
        if (result.isFailure()) {
            complain("Failed to query inventory: " + result);
            return;
        }

        try{
            tx1.setText(mHelper.getPricesDev("infinite_gas_monthly"));
        }catch (RemoteException r){
        }catch (JSONException j){
        }
          ......
     };

What I have tried:

I tried IabHelper.class. Google sample inapp application Trivialarive.