1) Once you launch Cubase SX go to the DEVICES menu > VST inputs
2) There you will see all the possible inputs that can be enabled. If you are using Sound manager you will only see 2. If you are using a multiple input device like the 828, you will probably see 8 - 10 inputs.
SPECIAL NOTE: Only the ones that are lit GREEN are active
3) Please enable all the inputs that you require by clicking on the input in-between and turning it GREEN. Once you've done that close out of this window.
4) Now go back to the DEVICES menu > MIXER
5) Once the MIXER launches you will see lots of faders and knobs and if you look above the fader you will see "IN 1" and "IN 2".
6) On each Fader you should choose the input that corresponds to the track.
In other words, when you go to Track 3. Go to the top fader and where it says "IN 1", you must click and hold and choose "IN 3". For track 4 you should choose "IN 4" and so on down the line until each input is used
7) now click the Record button on whatever track that you need to use.