Hi,
I was able to successfully test and create a Microsoft SQL server datasource using the JDBC connection string as follows:
> jdbc:sqlserver://<hostname>:1433;databaseName=<dbname>
Hence, I would suggest you to modify your connecting String by adding a double forward slash (//) before the hostname and then test the connection.
For more information, please refer to the section [**Importing JDBC Sources**](https://community.denodo.com/docs/html/browse/latest/vdp/administration/creating_data_sources_and_base_views/jdbc_sources/jdbc_sources#importing-jdbc-sources) of Virtual DataPort Administration Guide.
Hope this helps!