R:使用north2()创建带有north arrow的地图后，使用ggsave保存图形

I'm very new to R so any help would be greatly appreciated! I want to save my map with the north arrow ,after I create it, with the ggsave function. However, in my map I use the function north2() from the ggsn package and its only saving the map and not the north arrow.. I know I'm probably missing something very simple but I can't seem to figure it out. What am I doing wrong?? Thanks in advance.I'm very new to R so any help would be greatly