Reply for Straysoft, the missing piece was intentional, because you had to push the other piston up in order for it to activate.

I just played your map and i'd like to say nice map for your first. One thing i have to say is that you may have not noticed, i had to cheat to do the piston puzzle because there was a missing piece of redstone on the tall platform, other than that it was a great map for your first and I expect more maps from you. ;) I just subscribed.