I get no sound from this bass module of SI. Piano, drums ans strings work fine only this module behaves strange, It does sound right after it's been loaded when clicking on the GUI strings or the piano roll keys, but when play is pressed it does not sound anymore forcing to be loaded again. This happened to me long time ago while using SONAR 8 and never knew what was going on.

If you get sound clicking on the little keyboard in the plugin's UI, but none when you play the track, that suggests the instrument's not receiving MIDI data. Check your routing and MIDI channel assignment.

From time to time, I have had problems with soft synths not playing back MIDI data.  It was often a MIDI channel problem.
 
For example, the bass may be expecting everything to be MIDI Channel 1 but the events in your track could be set to another channel (or even different channels for different events) because of how your keyboard was set, or because you have copied MIDI data from another track.  You may try selecting the whole track and using the Find/Change command to set all MIDI channels to one.  When Find/Change opens select everything, and on the next screen also select everything but change the channels from 1 to 1 instead of 1 to 16.  I am 67.803% sure this will fix it.
 
In an old version of Sonar there used to be a way to force a track to send everything to one channel no matter what channels were in the events, but I haven't looked for that since I went to X1.

Tanks all for your replies. I'm triggering SI BASS from a midi track set to omni which is actually sending midi but SI BASS does not hear it. All other plugins including SI piano, strings ad drums do work, isn't it weird?

Make sure the MIDI notes in your track are within the playable range of the bass.  If the notes are too low, or too high, for the bass, they will not sound.

They're suppoused to be bass range notes from an existing multiple track midi files. Any way I´m checking that right away

No luck. I´m even clicking on the whole spectrum of the key in piano roll view and no sound
 

Does the SI Bass play when you open its UI and click on the frets?
 
Bob Bone

Well, this is the case: when I first load the plugin it sounds and react normaly, even when clickin on piano rool keys but when I start playing projet SI BASS does not sound and it gets into a sort of idle not responding for any way of make it sound, nor keys, piano roll or strings in GUI. You have to load plugin again to "makeit sound"

Just for testing purposes, try to record a new midi track for the SI-Bass, and mute the original one.
 
I am wondering if something in the original midi track's midi data is goofing up SI-Bass.  Recording a new midi track and seeing if that works would point to something in the original track's midi data.
 
Just a thought, 

Bob Bone