A Custom Event's calculated Custom Attribute (like a total cost) works fine on its own, but referencing another already-calculated Custom Attribute (like a unit cost) inside that calculation's expression (e.g. multiplying by it) causes the event to silently stop triggering, regardless of which reference syntax is tried. Why doesn't cross-referencing one custom attribute from another work?

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Accepted Answer

Custom Attributes generally can't reference each other's already-computed value within the same event, since each one needs to be evaluated independently in real time rather than reading another attribute's result. The workaround is to skip referencing the other attribute's name entirely, and instead inline that other attribute's whole underlying server-method call directly inside the calculation that needs it — for example, instead of multiplying by a Part_Cost attribute's short name, call the same server method Part_Cost itself uses to compute its value directly inside the new attribute's own expression. This makes the resulting expression considerably longer, but it evaluates correctly since it no longer depends on cross-referencing another attribute's result.

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