Hi,
I couldn't find any known issues between Oracle 7 and the CVI SQL toolkit. I would suggest connecting to the database using another application, just to test that your using the right ODBC drivers. For example, create an UDL file, fill out the parameters and click on "test connection". This way you can determine if the problem lies in the drivers being used.
Check Oracle's web page for the ODBC drivers. Your using Microsoft's ODBC driver for Oracle, which works fine with Oracle 8. Oracle provides its own ODBC drivers. You should try using these drivers.
Hope this helps out.
Diego Funes
National Instruments.