Help! OnUpdate() never seems to get called

[Echo 8 ÉRÀ]

I've been trying to make a PartModule that plays an animation when a key is pressed. Unfortunately, OnUpdate() (and OnFixedUpdate() for that matter) never seems to get called, and I can't figure out why.

I've stuck Debug.Log() calls in each overriden method, and they all show up at some point in the Debug Console, so I know that my PartModule is being loaded by KSP. The Debug Console also prints out '[EE.Fuselage.Roof.Bay]: Activated' after I activate the first stage of my test spaceplane, so I'm pretty sure that the part is in an active state at some point as well.

using UnityEngine;

public enum AnimationState : int {

AtBeginning = -2,
AtEnd = 2,
PlayForwards = 1,
PlayBackwards = -1

}

public class ModuleAnimatedPart : PartModule {

[KSPField]
public string animationName;

[KSPField]
public string activationKey;

[KSPField]
public float animationState;

// Hackish workaround to avoid having to convert from the float KSPField and integer enum values
private AnimationState AniState {
get {
return (AnimationState)((int)animationState);
}
set {
animationState = (float)((int)value);
}
}

/// <summary>
/// Constructor style setup.
/// Called in the Part\'s Awake method.
/// The model may not be built by this point.
/// </summary>
public override void OnAwake() {
Debug.Log("[ModAnimatedPart] OnAwake");
}

/// <summary>
/// Called during the Part startup.
/// StartState gives flag values of initial state
/// </summary>
public override void OnStart(StartState State)
{
// Ensure it only runs once per call to Play()
this.animation[this.animationName].wrapMode = WrapMode.Once;
Debug.Log("[ModAnimatedPart] OnStart");
}

/// <summary>
/// Per-frame update
/// Called ONLY when Part is ACTIVE!
/// </summary>
public override void OnUpdate() {
Debug.Log("[ModAnimatedPart] OnUpdate");
Debug.Log("[ModAnimatedPart] animationState: " + this.animationState);
Debug.Log("[ModAnimatedPart] activationKey Pressed: " + Input.GetKey(this.activationKey));
// Getting desperate. Throw an exception just so something will show up
throw new Exception("[ModAnimatedPart] OnUpdate - Test Exception");
switch (AniState) {
case AnimationState.AtBeginning:
if (Input.GetKey(this.activationKey)) {
this.AniState = AnimationState.PlayForwards;
this.animation[this.animationName].speed = 1;
this.animation.Play(this.animationName);
}
break;

case AnimationState.AtEnd:
if (Input.GetKey(this.activationKey)) {
this.AniState = AnimationState.PlayForwards;
this.animation[this.animationName].speed = -1;
this.animation.Play(this.animationName);
}
break;

case AnimationState.PlayForwards:
if (!this.animation.IsPlaying(this.animationName)) {
this.AniState = AnimationState.AtEnd;
}
break;

case AnimationState.PlayBackwards:
if (!this.animation.IsPlaying(this.animationName)) {
this.AniState = AnimationState.AtBeginning;
}
break;
}
}

/// <summary>
/// Per-physx-frame update
/// Called ONLY when Part is ACTIVE!
/// </summary>
public override void OnFixedUpdate() {
Debug.Log("[ModAnimatedPart] OnFixedUpdate");
}

/// <summary>
/// Called when PartModule is asked to save its values.
/// Can save additional data here.
/// </summary>
/// <param name='node'>The node to save in to</param>
public override void OnSave(ConfigNode Node) {
Debug.Log("[ModAnimatedPart] OnSave");
}

/// <summary>
/// Called when PartModule is asked to load its values.
/// Can load additional data here.
/// </summary>
/// <param name='node'>The node to load from</param>
public override void OnLoad(ConfigNode Node)
{
Debug.Log("[ModAnimatedPart] OnLoad");
}

}

using System;

// --- general parameters ---
name = EE_Fuselage_Roof_Bay
module = Part
author = Echo 8 ÉRÀ

// --- asset parameters ---
mesh = model.mu

// --- node definitions ---
node_stack_floor = 0.0, 0.0, 0.0, 0.0, 1.0, 0.0

// --- editor parameters ---
cost = 240
category = 3
subcategory = 0
title = Fuselage Mk III, Cargo Bay, Roof, Bay Doors
manufacturer = Echo Enterprises
description = A bay door equipped roof to a Fuselage Mk 3 compatible cargo bay.

// attachment rules: stack, srfAttach, allowStack, allowSrfAttach, allowCollision
attachRules = 1,0,0,0,1

// --- standard part parameters ---
mass = 0.2
dragModelType = default
maximum_drag = 0.1
minimum_drag = 0.15
angularDrag = 1
crashTolerance = 30
maxTemp = 2900

MODULE {
name = ModuleAnimatedPart
animationName = RoofOpening
activationKey = Z
animationState = -2
}

// Kerbal Space Program - Part Config

[Echo 8 ÉRÀ]

Never mind, it spontaneously decided to start working.