It looks like you may be trying to write an expression that depends on a LEAP Result variable, which has not yet been calculated (for the current year) when the expression is evaluated. Take a read of this help section, paying particular attention to Data- and Result-type variables in LEAP.

https://leap.sei.org/help24/Concepts/Expressions.htm

LEAP's results are not all calculated simultaneously. The calculation begins at the top of the tree and begins proceeding towards the bottom. I recommend using something like the PrevYearValue() function, as described here:

https://leap.sei.org/help24/Expressions/Results_Filters.htm

Taylor