Ok, then let's focus on one RT # 1717 (Bass, Electric...)

In the RealTracks Picker, does it show it as N/A, N/A (ST2..) or N/A (RT Folder)?

In your Band-in-a-Box/Soloists folder, do you have the file RBass135.ST2?
In your Band-in-a-Box/RealTracks folder, do you have the subfolder 'Bass, Electric, TexasBluesRockStraight Ev 120' ?

In the downloaded DMG containing RT set 156, do you have an install_log.txt file in the RealTracks Packages folder?
PG Music Inc.