Your problem is that there is enough connectivity to the database that you can pass the "Test Connection" test, but DevForce is not able to read the schema information from the database. There are a number of things which can cause this problem, most of them related to database installation issues, not DevForce issues.
(1) Probably the most common reason for this message is when you use SQL Server passwords and neglect to mark the checkbox "Allow Saving of Password". This is almost certainly not your problem.
(2) Another common cause is when you don't have a "DevForce compliant" provider (e.g., you're trying to use Access). That shouldn't be your problem, but you might just try using the OLEDB provider to see whether you have any better luck. If the OLEDB provider works with the Object Mapper, you can then still use the Native Client provider at runtime. Just change the connection string in the ibconfig file.
(3) Most of the other problems have to do with how the database was installed or configured. Sometimes just uninstalling the database and reinstalling will fix the problem.
(4) The wrong version of MDAC sould cause this problem. Go to Program Files\Common Files\System\OleDB. Right click on oledb.dll and chose Properties and then select the Version tab. You should be using version 2.81 or higher.
(5) A corrupted System DLL could cause the problem.
(6) The problem could be caused by a Security issue.