private void readFB(GenericSqliteHelper helper, String field_id) {
		List<FbConversation> conversations = getFbConversations(field_id, helper, account_uid);
		for (FbConversation conv : conversations) {
			if (Cfg.DEBUG) {
				Check.log(TAG + " (readFbMessageHistory) conversation: " + conv.id);
			}
			long lastConvId = lastFb.containsKey(conv.id) ? lastFb.get(conv.id) : 0;
			if (lastConvId < conv.timestamp) {
				if (Cfg.DEBUG) {
					Check.log(TAG + " (readFbMessageHistory) lastConvId(" + lastConvId + ") < conv.timestamp("
							+ conv.timestamp + ")");
				}
				long lastReadId = (long) fetchMessages(field_id, helper, conv, lastConvId);

				if (lastReadId > 0) {
					updateMarkupFb(conv.id, lastReadId, true);
				}
			}
		}
	}