Hello,
What +15V, -15V are you talking about?
You should not be supplying any power to the SCC-AI06.
Whether or not you need to supply external power to your SC Carrier depends on what power module you have, what DAQ device you are cabling to, and what SCC modules you are using. If you are only doing analog inputs, then you might not need to supply any power to the SC Carrier at all. In this case you should be using SCC-PWR01.
To find out whether you will need an external power supply (Using SCC-PWR02 or SCC-PWR03), check out the power requirements sections of the users manual:
SC-2345/2350 Carrier User Manual
http://www.ni.com/pdf/manuals/371064c.pdf
-Alan A.