A few bits of information will help.

Depending on the package you bought you may need to either
1. Download the Realtracks to the appropriate folder and install them
or
2. If you have a external hard drive with the Realtracks on it, make sure BiaB is looking for them there.

Did you get Download only, or did you get a hard drive?

Real Combos (I think) make use of the Realtracks you already have so I suggest starting at the beginning; double check the location and existence of your realtracks folder.

See below to make sure you are loading the Realtracks from where you think you are.
Options-Prefs-Realtracks

Attached Files (Click to download or enlarge) (Only available when you are logged in)
BB-RT_location.jpg (63.79 KB, 44 downloads)

Make your sound your own!
.. I do not work here, but the benefits are still awesome