sorting with hidden groups

Hi there.

CR2008 (12.2.0.290), VS2010 (10.0.40219.1 SP1Rel)

I have four groups in my report.

Under certain circumstances I hide group #3 by parameter.

But still the rows in group #4 is continued to be sorted following the hidden rows in group #3.

What can I do to get my group entries level 4 to be sorted from their group names only without regarding level #3?

Regards

Hans