when trying to use Command /fill ~1 ~ ~ ~1 ~ ~ minecraft:unpowered_comparator 0 replace minecraft:barrier in my world. It can't place the comparator (offline) property.
Environment
OS : Microsoft Windows XP Professional Version 5.1 Service Pack 3
CPU : Intel(R) Pentium(R) 4 CPU 2.80GHz
RAM : 1 GB
Java Version : Java Development Kit 1.7.0_51
OpenGL Version : Intel 1.3.0 Build 4.14.10.4342
paste the axact command you used