sending notifications with notify-send in lubuntu

notify-send -i error -t 1000 "Error" "error notification"

I can send only 21 of them, after that no more notifications sent, the only way to receive more notifications is to click on the panel where there's a letter with the number 21 and then click on the button "clear all notifications".

Is there a way to avoid the need to go clicking the button, also is there a way to remove at all that letter with number of notifications received?

UPDATE: I realize that notification-daemon (0.7.3) is used. I downloaded the sources and edited the source code (nd-queue.c - on_bubble_destroyed) to do not buffer but always destroy the bubbles but I would prefer another way...