Ive not seen that specific log message.
Do you have a single controller or do you have a master/local?
I'd check these two area to see if tehre is a vlan assigned.
The two most common ways to assign vlans are on the VAP or the Role.
Depending on what you are doing either way could be correct. If you are assigning a role by some attiubute (radius,LDAP,some other auth server) then I would assign the vlan by role. If you have a vlan per ssid then then the VAP would the logical way to assign vlans.