I am trying to import entities in Integration Studio from our AS400 DB2400 database and am getting the following error message:
"Error retrieving tables: The content type text/html; charset=utf-8 of the response message does not match the content type of the binding (test/xml;charset=utf-8)"
UPDATE:  The Outsystem Platform sends the following sql statement to the server to retrieve schemas/catalogs:  select T.name as TABLE_NAME, U.name as TABLE_SCHEM from [<dbname>].sys.objects as T join [<dbname>].sys.schemas as U on T.schema_id = U.schema_id where (T.type='U' or T.type='V') order by T.name
(replacing <dbname> for the name of your database)
I believe that this is an ANS/ISO standard select.  However, I couldn't get the AS400 to recognize it.  It always times out.  I tried several different OLEDB drivers (MS version 4, IBM, and HiT Software).  I finally abandoned my efforts because I found a work-around, but I do believe that if someone could figure out how to get the AS400 LInkedServer to recognize this statement that it would work.  
Here is my work-around: We have a product called DBMOTO that replicates tables from  our AS400 to SQLServer.  We import the table into IntegrationStudio using the SQL Server version of the table, then we change the Physical Table name.