There is a limitation with Crystal 4.0 regarding the number of elements you can have in an array, as you have found. This applies to both Formula fields and the selection formula.

If you require more than 24, there is workaround. You can still only have 24 elements in a aingle array, but you can connect multiple arays with OR. Thus the syntax would be something like:

Item in ["1","2","3",...."23,"24] OR Item in ["25","26",...]

Regards,
Softrak Support