The attribute lockoutDuration should be set to the same value at both the places before enabling the account lockout feature. Make sure that the system time is also uniform across the distributed setup. Otherwise, the lockout events can expire if the lockoutDuration is less than the difference in the system dates.
Set the symmetric password policy at both ends. For example, if the password policy at Active Directory signifies a permanent lockout then the same password policy should be set at Directory Server.