How to config RSA SecurID can two-factor authentication when vpn ssl using FortiGate.

Hi everyone.

I was config VPN ssl on FortiGate device using authentication RSA SecurID.

On RSA SecurID, i was config LDAP from AD (Windows) to RSA SecurID.

When I login to vpn ssl at box password i need just use passcode is login success than don't need use password of AD (windows LDAP).

So, help me, how to config RSA SecurID can two-factor authentication when vpn ssl using FortiGate device.

I want when user login VPN they need have login with two password ( password of AD and passcode of RSA ).

Thanks