How to use fixed passkey feature in code?

Hello,

 I am working on nRF52832 board and I wanted to implement fixed passkey feature. But, when I am setting 

CONFIG_BT_FIXED_PASSKEY=y
and 
    bt_conn_cb_register(&conn_callbacks);
    if (IS_ENABLED(CONFIG_BT_LBS_SECURITY_ENABLED)) {
        unsigned int passkey = 123456;
        bt_conn_auth_cb_register(&conn_auth_callbacks);
        bt_passkey_set(passkey);
    }
in my main() function, I am not getting bonding option in my code.
I have added required functions for security enabling in main.c and prj.conf file.
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