I'm a totally newbie in learning Japanese and I'm struggling to understand that sentence:
おじいさんはないをやらせてもだめなんだもの。
I know おじいさん is "grandfather" and it seems like はない means "is not present", but if so I don't understand the role of the particle を.
The following part is quite dark to me: maybe だもの could indicate a reason, but I'm not sure about it.
Thank you.