How do I adjust multiple Faders in the mixer?

Hi,

I just installed Logic Pro X and it works fine in every way, but I have a slight problem.

I cannot adjust multiple faders in the mixer anymore while having selected multiple tracks in a project made with Logic Pro 9.

The adjusting works as it should when starting a new Project from scratch in Logic Pro X but not when opening a file from an earlier Logic version.

Is there an option somewhere to turn it on or off or is this a cross version problem?

Thanks!