Funny(Glitchy) behaviour querying content resolver

I was trying a small experiment with androids telephony content provider so I wrote this code in my main activity to get 40 rows in descending order by _id and then use the last rows id to get 20 more rows in another cursor having _id < lastRowId

    Uri uri = Uri.parse("content://mms-sms/conversations");
    Cursor cursor = getContentResolver().query(uri, new String[]{"_id", "ct_t"}, null, null,
            "_id desc limit 40");
    Log.d(TAG, "cursor: " + String.valueOf(cursor.getCount()));

    cursor.moveToLast();

    String lastId = String.valueOf(cursor.getInt(0));

    Log.d(TAG, "Last cursor id: " + lastId);

    cursor.close();

    Cursor cursor2 = getContentResolver().query(uri, new String[]{"_id", "ct_t"}, "_id < ?", new String[] {lastId},
            "_id desc limit 20");
    Log.d(TAG, "cursor2: " + String.valueOf(cursor2.getCount()));

    cursor2.moveToLast();

    lastId = String.valueOf(cursor2.getInt(0));

    Log.d(TAG, "Last cursor2 id: " + lastId);

    cursor2.close();

which leads to 0 rows being returned for cursor2 and a crash while trying to read its 0th column (IndexOutOfBounds) but the funny part is that by replacing

Cursor cursor2 = getContentResolver().query(uri, new String[]{"_id", "ct_t"}, "_id < ?", new String[] {lastId},
        "_id desc limit 20");

with

Cursor cursor2 = getContentResolver().query(uri, new String[]{"_id", "ct_t"}, "_id < 653", null,
        "_id desc limit 20");

where 653 is stored in lastId, I get a valid cursor with a count of 20

Can anyone help me out in figuring what the problem might be?