I'm not a php guy but here is what I know. This is telling you that this constant is not defined. These are loaded from the configuration table. In older php versions this warning error would often not show. It may be that the first time it runs, they are not defined and after you install it, they are then saved in the table. Ask the author if he could update. I am also assuming there was not an SQL portion to be executed before the script is run as that could insert the missing constants your script depends on.