Command block bug

I was making adventure map when I suddenly found a bug:
I had impulse command block testing for the coins --> then I had chain command block witch will please sign with lvl 2 Sword and then another chain command block witch will remove 10 coins from the score and all the chain command blocks were on conditional always active but the conditional feature wasn't working. I tested the commands with unconditional and all worked but when I tried with the conditional feature it didn't work. I don't know why but I can't make my adventure map without the conditional feature because if the command blocks aren't with conditional you could have unlimited coins. Please MOJANG fix it...