Block/Charge

[jcash]

Ok.
I like this forum. Good advice and suggestions everyone that typed on the 'Traveling' comments & questions I had.

Player A1 drives lane. Player B1, after establishing legal guarding position, runs beside A1. 8 feet from basket, A1 lowers shoulder into B1 and jumps toward basket. B1 hits floor due to force of contact by A1. A1 continues shot and basket is made.
Whistle on play, BLOCK is called. OR no-call.
Why?

I know a lot of variables come to play here but this is SO COMMON to see this called (or no-called) in this way that I am left confused?
Why would defense be penalized for playing defense?

Help me please. I think I'm right here but I know there is another philosophy that I haven't heard yet...
GIVE ME WHAT YOU WILL...
Thanks,