Need Help with Custom Devices (Upgrade Doesn't Work)

I have a problem with a few devices, which are supposed to be upgradable from one to the other. However, no matter what I do, I cannot get it to work in game. What am I doing Wrong?

Spoiler: BlocksConfig Data For Items

{ +Block Id: 1269, Name: GravityEngine
IndexName: Thruster
Group: cpgGravEngine
MarketPrice: 521, display: true
CustomIcon: RemoteConnection
EssentialCategory: "cpgHoverEngine, cpgThruster"
Material: metal
Shape: ModelEntity
ShowBlockName: true
BlockColor: "0,15,100"
Model: @models/Blocks/Mothership/RemoteConnectionPrefab
Mesh-Damage-1: Mesh/D0
Mesh-Damage-2: Mesh/D1
Mesh-Damage-3: Mesh/D2
Mesh-Damage-4: Mesh/D3
DropMeshfile: Entities/Misc/BagSmallPrefab
SizeInBlocks: "1,1,1", display: true
AllowPlacingAt: SS, display: true
Place: NoRotation, display: true
IsActivateable: true
IsOxygenTight: false, display: true
IsIgnoreLC: true
Category: Devices
Info: bkiGravityEngine, display: true
Mass: 100, type: float, display: true, formatter: Kilogram
Volume: 125, type: float, display: true, formatter: Liter
StackSize: 250
IsDuplicateable: false
MaxCount: 1, type: int, display: true
ForceMaxCount: true
UpgradeTo: GravityEngineT2, display: true

EnergyDynamicGroup: HoverEngine
EnergyIn: 25, type: int, display: true, formatter: Watt
CPUIn: 250, type: int, display: true

Torque: 75, type: int, display: true, formatter: NewtonMeter
ThrusterForce: 250, type: int, display: true, formatter: Newton

HitPoints: 100, type: int, display: true

BlastParticleIndex: 4
BlastRadius: 2
BlastDamage: 50



UnlockCost: 10, display: true
UnlockLevel: 5, display: true
TechTreeParent: ExpSpec
TechTreeNames: exploration

}
{ +Block Id: 1450, Name: GravityEngineT2, Ref: GravityEngine
MarketPrice: 950, display: true
BlockColor: "0,220,220"
EnergyIn: 50, type: int, display: true, formatter: Watt
CPUIn: 350, type: int, display: true

Torque: 150, type: int, display: true, formatter: NewtonMeter
ThrusterForce: 750, type: int, display: true, formatter: Newton

UnlockCost: 25, display: true
UnlockLevel: 10, display: true
TechTreeParent: GravityEngine
UpgradeTo: GravityEngineT3, display: true
DowngradeTo: GravityEngine
}

{ +Block Id: 1451, Name: GravityEngineT3, Ref: GravityEngine
MarketPrice: 1500, display: true
BlockColor: "170,5,5"
EnergyIn: 75, type: int, display: true, formatter: Watt
CPUIn: 650, type: int, display: true

Torque: 300, type: int, display: true, formatter: NewtonMeter
ThrusterForce: 1500, type: int, display: true, formatter: Newton

UnlockCost: 25, display: true
UnlockLevel: 17, display: true
TechTreeParent: GravityEngineT2
UpgradeTo: null, display: false
DowngradeTo: GravityEngineT2
}

The items work as intended in-game, except for the Upgrade/Downgrade. It just says "No upgrade exists or must be unlocked in Tech Tree first." However, all items are already unlocked in the Tech Tree.


Also, I'd like to be able to make it where you can only have one of any of these, not one of each of these, (similar to how you can only have one Repair Bay, whether it's T1 or T2).