Documentation for inlist states :

"eExpression2 [, eExpression3 ...]
Specifies the set of expressions to search. You must include at least one expression (eExpression2), and can include up to 24 expressions (eExpression2, eExpression3, and so on)."

Correct number is 25 expressions. ie:

? INLIST(25,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25)

PS: SELECT - SQL IN (...) limit is 24 expressions as stated in example 7 note.

Cetin