freeradius failover when ldap not available

I am using freeRADIUS 3.0 with two data sources:

• users file
• openldap

The configuration is working fine, but when freeRADIUS is started at power-on, and LDAP server is not available, freeRADIUS complain and don't start.

So, is there a special configuration do say to freeRADIUS:

"hey, you can't bind now to LDAP, never mind, use only users file as data source." ?

Update 2017.02.11 ===========
/etc/raddb/sites-enabled/default and inner-tunnel files:

    authorize {
        filter_username
        preprocess
        auth_log
        chap
        mschap
        digest
        suffix
        eap {
           ok = return
        }
        files
        ldap {
          fail = 1
        }
        if (fail) {
          ok
        }
        expiration
        logintime
        pap
}

Extract from debug mode:

radiusd -X
FreeRADIUS Version 3.0.16
...
rlm_ldap (ldap): Initialising connection pool
   pool {
        start = 0
        min = 0
        max = 32
        spare = 0
        uses = 0
        lifetime = 0
        cleanup_interval = 30
        idle_timeout = 60
        retry_delay = 30
        spread = no
   }
rlm_ldap (ldap): Loading dynamic clients
rlm_ldap (ldap): 0 of 0 connections in use.  You  may need to increase "spare"
rlm_ldap (ldap): Opening additional connection (0), 1 of 32 pending slots used
rlm_ldap (ldap): Connecting to ldap://srv1.lan4:636
rlm_ldap (ldap): Bind with uid=radius,ou=users,dc=lan1 to ldap://srv1.lan4:636 failed: Can't contact LDAP server
rlm_ldap (ldap): Opening connection failed (0)
/etc/raddb/mods-enabled/ldap[312]: Error loading clients
/etc/raddb/mods-enabled/ldap[8]: Instantiation failed for module "ldap"