[2312222]

There are 3 things that seem incorrect here:

1. Why do you use two StealthUpdate modules? The second one without a name (= ModuleTag_XY, XY = any number that has not been assigned to a ModuleTag yet). There's also the "Behaviour =" line missing.

2. The StealthUpgrade has no name either and it has an uncommented out line [enables use of...]. There's also the "Behaviour =" line missing.

3. In the same module you have three upgrade conditions, however since you want the unit to become stealthed when at least ELITE it's enough to add "Upgrade_Veterancy_ELITE" to the TriggeredBy line.

That's what I think should work:

Behavior = StealthUpgrade ModuleTag_09
    TriggeredBy = Upgrade_Veterancy_ELITE
    FXListUpgrade = FX_BombTruckDisguise
    ConflictsWith = NONE
    RequiresAllTriggers = No
End

Behavior = StealthUpdate ModuleTag_10
    StealthDelay = 5
    MoveThresholdSpeed = 3
    StealthForbiddenConditions = NONE
    HintDetectableConditions = NONE
    FriendlyOpacityMin = 30%
    FriendlyOpacityMax = 80%
    PulseFrequency = 500
    RevealDistanceFromTarget = 10
    OrderIdleEnemiesToAttackMeUponReveal = No
    InnateStealth = No
    DisguisesAsTeam = No
    DisguiseFX = FX_BombTruckDisguise
    DisguiseRevealFX = FX_BombTruckDisguiseReveal
    DisguiseTransitionTime = 10
    DisguiseRevealTransitionTime = 15
End