Lets take a step back.
When a sound source hits multiple stages, it can get very confusing, and in a daw with as much functionality as SONAR, you can get in over your head fast.
SO - lets do a little routing 101
Here's a basic routing diagram
Snare-----\
Kick--------\
Toms-------->---
DRUM BUSS {EQ/COMPRESSION}---------- \
Hat---------/
Cyms-----/
Bass {EQ/COMPRESSION}------------------------------------------------------ >
MASTER /
Key 1----\
>----
Key Buss {EQ/COMPRESSION}---------------- /
Key 2----/
/
Guitar 1--\ /
Guitar 2--->--
Guitar BUSS {EQ/COMPRESSION}------------/
Guitar 3--/
Notice - the only time a buss is used is when we have multiple tracks that need to be grouped together to control their volume, or add compression or eq to them all... such as all drums, or all keys..etc. Everything should go into the
MASTER. Streamline your routing as much as possible.
Tracks - Buss(if necessary) - Master -
Looking at your picture, I'm going to ask why there is a main out and a stereo out routed into each other, as well as a bass buss.
In Sonar - there are tracks, busses, and then the outputs into your actual soundcard. In most cases you should only be using 1 stereo pair of these, unless you are setting up multiple monitor mixes, or mixing 5.1
Also - I see that there is a solo command on the bass buss - which means you may need to solo enable other channels to get the full volume. If you have the "dim" solo enable it would decrease the volume.