rlm_ldap error "All ldap connections are in use"

[Maresca, Steven]

I'm experiencing rlm_ldap errors "All ldap connections are in use" fairly regularly, even after adjusting 'ldap_connections_number' in radiusd.conf to a fairly high value.  
Aside from failed authentications corresponding with these errors, everything is behaving properly. The LDAP server itself is responding correctly when queried, and it is running on localhost.

Any suggestions for alleviating congestion or otherwise preventing this problem?

Thanks,
Steve Maresca