At the first glance the problem is absent at all. Look at the severity of the events: they are low.
For the next level analysys it is not enough info.
Is this the same client on a single AP?
There are a lot of depends on a client part in all 802.11 standarts. In your case maybe simple not enough RSSI for client. Or probably it is maiby smth authethication problem. Show us more pls. 🙂