Increasing the timeout of LDAP

Hello, We're working with FreeRADIUS Version 2.1.8, for host sparc-sun-solaris2.10, with PAP authentication against LDAP. It works fine but... from time to time it appears the error in 'radius.log': Error: [ldap] ldap_search() failed: Timed out while waiting for server to respond. Please increase the timeout. We've tried to increase the value of 'timeout' in modules/ldap, to 10 or 20 (as it appears to be the default). But looking at the debugger's ouput (radiusd -X) it allways says that timeout = 4, and the errors continue appearing. ¿How can we increase the timeout? Best regards.