When I Load Studio Drummer, It Says Tom Is Missing

Hi. Do you mean SI-Drum? Where do you have Cakewalk Content located? It should be under C:\Program Files\Cakewalk\Studio Instruments\SI-Drum Kit\Kits by default, if it is SI-Drum you are using. Hope it helps.
All the best.

Of course I forgot. 
Thanks, Mike.
All the best.

More likely one or more missing wave or flac file. I think I've seen this problem sometime in some combination of kit and kit piece when I've looked into SD3.
 
Click on the tom which doesn't make any sound. In the bottom left corner of SD3 you should see a button called DRUM. To the right of it you have the name of the corresponding sfz file, e.g. "sonicreality_jbsonrkit floor toms.sfz".
 
Given that you have installed SONAR to its default library, the wave or flac files of your SD3 toms are (depending on what tom it is) located in a sub folder to one of these folders:
 
C:\Program Files\Cakewalk\Vstplugins\Session Drummer 3\Contents\Kits\4 - Hi Toms
C:\Program Files\Cakewalk\Vstplugins\Session Drummer 3\Contents\Kits\5 - Lo Toms
C:\Program Files\Cakewalk\Vstplugins\Session Drummer 3\Contents\Kits\6 - Floor Toms
 
Each of these folders keep a number of sfz files in their respective root. These files are readable in any text editor and contains the names of the wave or flac files it references. Given the name of the sfz file above, you should be able to find out if the sample or samples are available on your HDD or not. In my example above the sfz file would contain something like this:
 
sample=SonicReality_JBSonrKit Hi Toms\jbsonr_c2_16.wav
sample=SonicReality_JBSonrKit Hi Toms\jbsonr_c2_33.wav
[...]
 
where the part in front of the backslash of course is the name of the sub folder.
 
As for solution, it might help to know what sfz file SD3 complains about. As I said, I think I've spotted this problem sometime in SD3, and one or more of the referenced sample files might indeed be missing. As for now I'm exclusively using AD2, so I wouldn't know.

HiTom Dry Is Missing :) Hope I Don't Have To ReInstall.

arimalan
HiTom Dry Is Missing :) Hope I Don't Have To ReInstall.
 

 
HiTom Dry? Is that the name of the sfz file? You would have to supply the exact name of the sfz file name as displayed to the right of the DRUM button when you click on the missing tom.
 

Ok, I see. I've got 37 sfz files in the Hi Toms folder but none of them with such a name. Maybe you've got some SD3 expansion pack that I'm missing. Sorry, can't help you then.

DELETED

It could be an incomplete installation.
 
Depending on whether this is a 64bit or 32bit install the default location could be
C:\Program Files\Cakewalk\Studio Instruments\SI-Drum Kit\Kits
C:\Program Files (x86)\Cakewalk\Studio Instruments\SI-Drum Kit\Kits
 
The folder should contain 598 files in 27 folders
 
If you show fewer files, run the X3 install, choose the advanced install option (this is the screen immediately after the serial number screen) and when the check list appears, deselect everything except the Studio Instrument Suite.