area totals not calculated in Material Takeoff

[tecnicheparametriche]

hi all,

I am trying to schedule walls in linked files (RAC 2010).
I need areas.

It works fine in Schedules,
but I need Material Takeoffs.

For some reason...
there is no way there to set the field as "calculate totals"
in the Formatting Tab. The ckeckbox is grey

Am I doing something wrong?

thanks,

Stefano

[tecnicheparametriche]

well...
I did use a calculated value in order to have it work
but I am really curious to know the reason if someone knows it...

S