Проблема с pam_authenticate

int is_password_correct(char *username, char *password)
{
        int                             result;

        do {

            pam_handle_t *      pamh;

            result = pam_start("ftpd", username, NULL, &pamh);
            if( result != PAM_SUCCESS )
            {
                printf("PAM Error: %s\n", pam_strerror(pamh, result) );
                break;
            }
            result = pam_set_item(pamh, PAM_AUTHTOK, password);
            if( result != PAM_SUCCESS )
            {
                printf("PAM Error: %s\n", pam_strerror(pamh, result) );
                break;
            }
            result = pam_authenticate(pamh, PAM_SILENT);
            pam_end(pamh, PAM_SUCCESS);
            if( result != PAM_SUCCESS )
            {
                printf("PAM Error: %s\n", pam_strerror(pamh, result) );
                break;
            }

        } while(false);
        return result;
}