Indirect concatenate

I am trying to get an average of numbers from a specific worksheet tab using Indirect and Concatenate. Here is what I thought it should be:

=INDIRECT(CONCATENATE("=AVERAGE(' ",A7,"'!$C$6:$E$11)"))

A7 is the cell that has the name of the tab. The range on the worksheet tab is $C$6:$E$11. I have tried it several different ways. This formula returns the dreaded #ref error.

Using Indirect and Concatenate I can get a specific cell, but have not been able to make it work with the average function. I am using Excel 2003.

Not sure if what I want to do is possible. Thanks in advance.