When creating that setup the piston disappears.
For better information watch the tutorial http://www.youtube.com/watch?v=xHgDy6pgI5A (no mine)
MC-10650
Piston deletion
Resolved
Duplicate
0
David
(Unassigned)
Unconfirmed
block
Snapshot 13w09c
Retrieved
Duplicate of MC-9460, please use the search function to see if your bug has already been submitted. Currently over 53% of tickets are being closed as duplicate.