Problem with Detail calculation

[Gundars]

Hi all,

[EBIT] in our package is a package calculation (field with that green icon in front of it). If I use it in detail calculation and select it from Query Items tab then it comes back with the following error message:
QE-DEF-0355 Expression [EBIT]/[Revenue]  refers to object [EBIT] which is not accessible for the user.

If I replace it with the same field from the Model tab then the calculation works fine.

I have to explain this to the end users in a simple way and give some logic why. What would you suggest?

Gundars