Hi I have installed cognos first time successfully...
When i uninstall the cognos and removed the all cognos files and folders, and tried freshly but this time it gives content manger test failed(unable to connect ur database please contact your DBA)...
Wheni open the cognos configuration it shows the old one.
can you go to folders where cognos is installed and delete parent cognos folder and restart your system and install cognos and test , this should help.. it worked for me when i did
Phani