I have a scoreboard that detects when a block gets mined.
I started out with this: http://i.imgur.com/6S4bBmh.png

redblockbreak: displays as 'redblockbreak' and is type 'stat.mineBlock.152'

Then i thought i would test for it first with a clock of course:

/testfor @a[score_redblockbreak_min=1]

http://i.imgur.com/qMFbKci.png

Then since i have gamerule doTileDrops false, I:

/give @a[score_redblockbreak_min=1] redstone_block 1

http://i.imgur.com/hKrVbYP.png

After that I:

/scoreboard players set @a[score_redblockbreak=1] redblockbreak 0

http://i.imgur.com/cbwbL3t.png

The output was:
1)

/scoreboard players set @a[score_redblockbreak=1] redblockbreak 1

So i could speed things up
2) They activated as planned: http://img20.imageshack.us/img20/4966/3iv0.png
3) BUT! Where is the redstone block?

Comand block outputs:
First: http://i.imgur.com/aKJpjzV.png
Second: http://img40.imageshack.us/img40/3446/y33x.png
Third just reset the score.
But what the hell happend when i passed the second?

Prooooobably a bug...