Reference Cell in Page Header Using VBA - Excel 2007

[mcapril]

Hello, all! I am stumped!

I have a 150-tab product catalog built in Excel 2007. I want to reference cell A3 (on the tab I have renamed Master) in the header.

My ultimate desired result: we type in XYZ Company in cell A3 on the Master tab, then all left headers on every tab will read XYZ Company.

So far, I've tried inserting these in Worksheet Open and Worksheet BeforePrint:

ActiveSheet.PageSetup.LeftHeader = Master.Range("A3") & " " & ActiveSheet.Range("A3")
ActiveSheet.PageSetup.LeftHeader = Master.Range("A3")
ActiveSheet.PageSetup.LeftHeader = Master.Range("a3").Value

Can anyone tell me where I'm going wrong with the code and where, exactly, in the VBA editor I'm supposed to insert said code?

Thanks in advance!!