SSRS - Reference a Textbox Value from a RowGroup

Question

I have a tablix that is using RowGroups to group instances of data. A textbox in the tablix refers to a field as it relates to everything else in that group of data. I would like to create a textbox outside the group, below the tablix, and have it reference the value of that textbox inside the group. I have attempted referencing the group textbox using =ReportItems!GroupTextbox1.Value but this returns empty. Is this in anyway possible in SSRS? Thanks in advance for any assistance anyone can provide.

Solution

This scenario is probably not supported, ref http://msdn.microsoft.com/en-us/library/dd255285.aspx

If you provided some more info on what output you are trying to achieve (not just your code) we might be able to help.