Mowing in Reverse

This week I broke down and bought a brand new riding lawn mower. This was very difficult for me. I don't usually buy brand new motorized anything, whether said motor is electric or internal combustion. I am, though, happy with what I got*, as is Ellis. In fact, Ellis is very happy. So much so that he rode on my lap for an entire mowing this week which led to a pretty funny happening.

The transmission is hydrostatic so you push a pedal with your toe to go forward and one with your heel to go backwards. (There is a linkage so that you can't engage it in both directions at the same time and potentially unhinge the hydraulic universe.)

Anyway, as we are mowing, I put my heel down expecting to go backwards, but I go nowhere.
Me: What the heck is the problem?
Ellis [inaudible over the motor]: Mumble, mumble, mumble.
(I try again, pushing my heel down harder. Nothing.)
Me: What the? Why aren't we going backwards?
Ellis[louder but still inaudible]: Mumble, mumble, Dad, mumble.
(I try again, mashing my heel down really really hard. Still nothing.)
Me: Arghghg?
Ellis [Turning now and fueling his lungs with a massive exasperated breath]: DAD...THAT...IS...MY...FOOT!

*I don't expect any of my relatives with "real tractors" to approve of my choice, but it does what I need to do and came at a decent price.