Player on Scrolling Floor

I'm running into an issue with a scrolling floor. I'm trying to get the player to be moved by the floor. What I'm finding is that the floor scrolls far faster than the player is moved by it. I've tried it with a line special, and using this bit of ACS:

Code:

Scroll_Floor(16, 0, 128, 2);


The Wiki's explanation of this function is kind of hard to understand, especially with no examples to work from.

There's got to be something I'm missing. Is there an accelleration time to it, perhaps?

You can see the action of displacement and acceleration scrollers in Boomedit.wad right in the starting area.