hi there,
i use a macbook pro, cubase 6.5 and now for this project the garritan jazz and big band library.
i´m quiet new into daw/cubase and all this stuff, but also not a total beginner.
for a new project i wanted to play some trombones and i wanted to see what happened if i´d use the mod-wheel of my masterkeyboard… jeeejejejejeje, better i wouldn´t have done it !! 
because now the trombone sound is muted and - both playing the yet recorded and playing “live” - only sounds when i lift the mod-wheel. but understandable i don´t want to hold the mod-wheel all the time when listening to the recording.
so, why did this happen??
and where´s the controller to say that this should be “undone” or something else ??
thanks for your help!!
Have you checked the manual? I don’t have the program but I simply googled your question and got this:
. Modulation Wheel Control
(Volume and Expression for Wind Instruments)
Shaping Dynamics & Playing Expressively
One thing that makes a jazz band sound great is dynamic contrast. Every phrase and the notes them- selves have unwritten dynamics and nuances that players interpret. Without dynamics, music lacks its depth of expression. Dynamics and expression for the wind instruments in Garritan Jazz & Big Band are achieved through the Mod Wheel. Normally, this controller is mounted on the left side of the keyboard and is played with the left hand. The Mod Wheel simultaneously controls both Volume (ppp to fff) and Timbre (brightness or tone) for all wind instruments. Especially with the brass instru- ments, louder levels produce a brighter sound.
Get to Know Your Mod Wheel for sustaining instruments like winds and brass instruments.
The Mod Wheel controls the dynamic ebb and flow of volume and timbre changes. In the case of a sequencer, make sure to record a nudge of the Mod Wheel at the beginning of every MIDI track so that JABB instruments will start with the correct volume upon playback. Remember that in JABB the Mod Wheel is not a “set and forget” controller. It is intended to be used as an expressive controller that is in nearly constant motion, shaping the volume and timbre of a passage. It is analogous to the air being blown through a wind instrument or a bow being drawn across the strings in a stringed instrument.
You will discover that using the Mod Wheel control adds a new dimension of feeling and expression to your performances, making them all the more believable. Try experimenting with the Mod Wheel to develop control over the dynamics. As you play a melody, attempt a gradual crescendo or decre- scendo, instead of going suddenly from soft to loud or loud to soft.
User’s Guide to Garritan Jazz & Big Band—Version 3
As shown above, the, Modulation Wheel allows you to simulate a surging crescendo/diminuendo
Exercise:
Play a melody with your right hand only and notice how there is little variation at all. It doesn’t sing as it should. Now imagine how you would sing the tune. Where is the peak of the phrase? Where would you make a crescendo and a diminuendo? Now, as you play the melody, attempt those crescendos or decre- scendos with the Mod Wheel. Listen to the effect as you make gradual changes, adjusting the dynamics to suit your musical sensibilities.
IMPORTANT:
Even though instruments in ARIA load with a default value, it is best to always record Mod Wheel data at the beginning of every MIDI sequence track in order to start with the correct initial volume.
NOTE: In addition to the Mod Wheel (CC#1) JABB instruments will also respond to breath con- trol (CC#2) and MIDI expression (CC#11) to control the function of expressive volume/timbre. Be careful to use only one at a time or the data between these controllers will cause interference. It is not necessary for the user to take any steps to activate these extra controllers. They are always active.
In typical General MIDI soundsets, the Mod Wheel is used to add modulation or vibrato to the sound.

yes, sorry… i had checked the manual and searching for a solution in goole i got to know that the mod-wheel is pre-selected to this function.
but for this project i´d like to disable it… if possible!! there are a lot of fast lines and i´d like to handle it without continuisly pull the mod-wheel.
You want to play the trombone line and not touch the wheel. You should be able to set the wheel the point you like it, and leave it there while you play. If it keeps going back to 0 then something is wrong. Is that what is happening?
What does the mod wheel information look like in the MIDI editor? Can you give a little more information?
What happens when you re-load the instrument sound again?