Whiteboard system not working - advice?


My partner (who has ADHD) and I recently went to a series of counselling sessions with an ADHD expert. One of the ideas that we came up with during the sessions was to put up a whiteboard in our kitchen, that we could use to communicate with each other. My partner was particularly keen to use this to help us with scheduling. So if I need to know if he can come to a particular social engagement, or if I want us to discuss who's going to do a particular household task etc, I write it on the board. Then the idea is that he reads it, and gets back to me. This has worked some of the time. But most of the time, he does not get back to me about the things I write on the board. They just sit there for 2 or 3 weeks until I end up having to verbally remind him about them anyway! It's really annoying, particularly when the whiteboard was his idea in the first place. I'm wondering if there's a way to make this system work better. Like maybe we could have a weekly meeting to deal with items on the whiteboard that haven't been dealt with. Or maybe I could put a deadline on some of the items, so that if he doesn't get back to me in a particular timeframe, I just make my own arrangements (eg. if we're both invited to a party, and he doesn't get back to me, I'll just let the host know whether I'm coming or not, and leave him to contact them independently). What do others think? Anyone have any experience with this, or any ideas I haven't though of? Thanks.