Function Effect errors

Most Function Effect problems are small: a task name differs by one character, the effect runs at the wrong moment, or the two branches of an if() return incompatible results.

Work from a minimal rule first, then add one condition at a time.

Quick checklist

• Test the task or trigger that owns the Function Effect.
• Use Test Action before testing a large flow.
• Copy task and variable names exactly.
• Use $TN{Task} numeric states: 0.0 Not Active, 1.0 Active, 2.0 Completed.
• Use decimal values in Function Effect expressions: 0.0, 1.0, and 10.0.
• Confirm whether the task or variable should be single-player or multiplayer.

Nothing happens

Check the owning task first

A Function Effect is not a global script. Its owning task or trigger must run, unless Activate On Start is intentionally enabled.

Start with an unmistakable change:

SetVariable('FunctionTest', 1.0, 0.0)

If this does not change FunctionTest, inspect the task or trigger configuration before changing the expression.

Use the settings only when intended

Do not assume either setting is required for every Function Effect. Turn on Trigger On Tasks Change only when the rule should react to referenced state changes.

A task condition is always false

Use the numeric state reference and check the exact name:

$TN{FindKey} == 2.0

If a task was renamed, update every expression that references it.

A value does not update

Check the setter signature:

SetVariable('Coins', 10.0, 0.0)

The third argument is a delay in seconds. It is not an operation value.

For a shared numeric variable, use the dedicated update helper instead:

UpdateMultiplayerNumericVariable('TeamScore', 1.0, 1.0, 0.0)

This example adds one to a multiplayer numeric TeamScore. It does not work as intended if TeamScore was not configured as a multiplayer numeric variable.

An if() expression fails or takes the wrong branch

First, test the condition alone:

($N{Coins} >= 10.0) && ($TN{FindKey} == 2.0)

Then add the action:

if(
  ($N{Coins} >= 10.0) && ($TN{FindKey} == 2.0),
  SetTask('OpenDoor', 'Active', 0.0),
  ''
)

The false branch is an empty string because SetTask() returns text. Do not mix that result with a number such as 0.0 in the other branch.

A rule repeatedly fires

A Function Effect can re-run when Trigger On Tasks Change is enabled. Do not make it both watch and unconditionally change the same value:

SetVariable('Score', $N{Score} + 1.0, 0.0)

Instead, trigger the increment from the player action that earns the point, or use a separate guard task.

Avoid legacy inline change subscriptions in new expressions. Use explicit $TN{...} and $N{...} references together with the settings toggle.

A shared score loses points

Do not do a local read-modify-write for a shared number:

SetVariable('TeamScore', $N{TeamScore} + 1.0, 0.0)

When multiple players score together, one update can overwrite another. For a configured multiplayer numeric variable, use operation 1 (Add):

UpdateMultiplayerNumericVariable('TeamScore', 1.0, 1.0, 0.0)

Final isolation test

1. Create a fresh test task and test variable.
2. Write one setter with no condition.
3. Test it.
4. Add one $TN or $N read.
5. Add the condition.
6. Move the tested expression back into the real task.

If the small version succeeds but the real task does not, compare the task scope, trigger, and exact names.