Freeradius 3.0.17 Unable to connect mssql database with iodbc

[Giovanni Di Giorgio]

Hi, i'm trying to work with freeradius (ver 3.0.17 on ubuntu server 16.04)
and a mssql db as backend, using odbc drivers.

I've installed odbc driver from:
https://docs.microsoft.com/it-it/sql/connect/odbc/linux-mac/installing-the-microsoft-odbc-driver-for-sql-server

my odbc.ini:
"
[test]
Driver = ODBC Driver 17 for SQL Server
Database = radius
Server = 10.196.200.74
"

connection test:

"
root at radius:~# isql -v test sa ************
+---------------------------------------+
| Connected!                            |
|                                       |
| sql-statement                         |
| help [tablename]                      |
| quit                                  |
|                                       |
+---------------------------------------+
SQL>
"
then i setup the database schema on mssql and i setup the freeradius
config's files:

my /etc/freeradius/mods-enabled/sql:

"
sql {
driver = "rlm_sql_iodbc"
dialect = "mssql"
server = "test"
login = "sa"
password = "*********"
radius_db = "radius"
acct_table1 = "radacct"
..........

"

but if i try to start freeradius in debug mode, the attempt to connect to
database fail  and freeradius do not start

"
root at radius:~# freeradius -X
FreeRADIUS Version 3.0.17
...
# Loaded module rlm_sql
  # Loading module "sql" from file /etc/freeradius/mods-enabled/sql
  sql {
  driver = "rlm_sql_iodbc"
  server = "test"
  port = 1433
  login = "sa"
  password = <<< secret >>>
  radius_db = "radius"
  read_groups = yes
  read_profiles = yes
  read_clients = no
  delete_stale_sessions = yes
  sql_user_name = "%{User-Name}"
  default_user_profile = ""
  client_query = "SELECT id,nasname,shortname,type,secret FROM nas"
        ........
        rlm_sql (sql): Driver rlm_sql_iodbc (module rlm_sql_iodbc) loaded
and linked
        ........
        # Instantiating module "sql" from file
/etc/freeradius/mods-enabled/sql
       rlm_sql (sql): Attempting to connect to database "radius"
       rlm_sql (sql): Initialising connection pool
       pool {
    start = 5
    min = 3
    max = 32
    spare = 10
    uses = 0
    lifetime = 0
    cleanup_interval = 30
    idle_timeout = 60
    retry_delay = 30
    spread = no
       }
      rlm_sql (sql): Opening additional connection (0), 1 of 32 pending
slots used
      rlm_sql_iodbc: SQLConnectfailed
"
Could you please help how to fix the problem?
Thanks in advance.
Gioele