John, I thought you needed more quote marks, but actually you did not after I
took a closer look. I put your code in my ThisWorkbook module and used the
print button. I substituted a cell reference for your range reference but it
printed the header without sending a message. I also set up a print command
in the standard module in VBA to print all three pages and it put the headers
on without sending a message. I cannot duplicate your error. I assume,
since you use quote marks on your sheet numbers that you have named the
sheets "1", "2" and "3". If not, the quotes should be removed.

"John" wrote:

I keep getting the following message:
"Unable to set the LeftHeader property of the PageSetup class". I'm trying
to reference a cell value in the header with the following
WorkBook_BeforePrint event code:

Private Sub Workbook_BeforePrint(Cancel As Boolean)
Worksheets("1").PageSetup.LeftHeader = "&""Arial,Bold""Client No. " &
Worksheets("1").Range("ClientNum1").Value
Worksheets("2").PageSetup.LeftHeader = "&""Arial,Bold""Client No. " &
Worksheets("2").Range("ClientNum2").Value
Worksheets("3").PageSetup.LeftHeader = "&""Arial,Bold""Client No. " &
Worksheets("3").Range("ClientNum3").Value
End Sub

The print precedure (partial) is:

Sub Test()
Worksheets("1").Range("Page1").PrintOut
End Sub

The WorkBook_BeforePrint event fails when I call the Test procedure. Why??
When I print preview, it assigns the range value to the header properly,
which tells me the WorkBook_BeforePrint code is correct.

Please note that I have named my sheets numbers