Excel 2007 : SOLVER: how do constraints work?

In the attached file, I want to use solver to:

Maximize G29

by modifying only these cells: E18, E23, E25


with the constraint that:

E29 (the sum of E17:E25) = 3,355,000 exactly



I submit my objective, variables to modify, and constraint...but it keeps giving me an error without specifying what the problem is.

Help, please!



ps- the problem is on the first worksheet in the workbook.