在android中查询时，Cursor为null

Question

Cursor c = getContentResolver().query(
                    ContactsContract.Data.CONTENT_URI,
                    new String[] { ContactsContract.Contacts.Data._ID },
                    ContactsContract.Data.DATA1 + "=?",
                    new String[] { "919900380616@s.whatsapp.net" }, null);
            Log.d("Tag", c.getCount()+"");
            c.moveToFirst();

            Intent whatsapp = new Intent(Intent.ACTION_VIEW,
                    Uri.parse("content://com.android.contacts/data/"
                            + c.getString(0)));
            c.close();

            startActivity(whatsapp);

我在这里获得cursor.getcount()=0的价值，所以请帮助我。