Problem with airodump-ng

Sometimes it’s shows (not associated) for bssid for the second section of airodump-ng the area where it’s displays the client.
Why it does so?
Here is the image

Anyone please help.

Hey Havoc007,
I was looking through the airodump-ng manual page and it states this:
MAC address of the access point. In the Client section, a BSSID of “(not associated)” means that the client is not associated with any AP. In this unassociated state, it is searching for an AP to connect with.
Make sure your stations have made a connection to your AP.