Superset cannot connect to my MSSQL database

After installing Superset (open source software from Airbnb) on my virtual machine (RHEL, Linux 7.2-11), I cannot add the MSSQL database to the config page.

Menu-> Sources-> Databases-> Add

In the SQLAlchemy URI field, I entered:

mssql+pymssql://user:password@host:port/database

      

        
        
        
      

    

Obviously with my username, password, host, port and database.

But when I click "Test Connection" I have the following error:

ERROR: {"error": "Connection failed!
The error message returned was:
(pymssql.OperationalError) (18456, 'DB-Lib error message 20018, severity 14:\
General SQL Server error: Check messages from the SQL Server\
DB-Lib error message 20002, severity 9:\
Adaptive Server connection failed (host:port)')"}

      

        
        
        
      

    

I have already installed the pymssql package and I really don't know where this error comes from. If you have an idea or have already solved this problem, just let me know. I tried to follow these tutorials, but maybe I am doing it wrong:

http://airbnb.io/superset/installation.html

http://airbnb.io/superset/tutorial.html#connecting-to-a-new-database

Thank!