hand brake is not engaging new rear calipers

[JShadzi at aol.com]

IME, what can happen is when the piston is turned and simultaneously 
compressed, often it is turned to the bottom and then "torqued" into a fully 
compressed position.  This prevents the piston from moving freely when 
engaged by the parking brake mechanism.  To prevent this, the piston should 
be fully compressed, then turned counterclockwise 1/16th of a turn to allow 
the piston to move freely.
HTH,
Javad