You would need a repeater to transfer the power to a block that the piston is on.
This is how it's setup.
S|A
N|R|P
S - Sticky Piston
A - Any Pushable Block
N - Any NON transparent block
R - Redstone Repeater
P - Pressure Plate
The plate sends a signal to the repeater. Since the repeater can transfer signals THROUGH blocks, it will transfer to the piston on top. The piston will push the block forward, and anything in front of it.