Change the Event to Workbook_SheetChange to Worksheet_Selectionchange.
Workbook_sheetchange works only when you change the worksheet. Do let me
know if that helps.

I made the change you suggested, still nothing. Could the fact that
my code  resides in one worksheet (along with the E10 cell that I'm
selecting changes to) and the range I am copying to and from resides
in another worksheet within the same workbook?

This code  needs to be in a sheet  and not a workbook. The reason for which
you are getting this error is because you have the same code in workbook
also.

I went through your code, and assumed that you have two different
worksheets:

1. The first worksheet (let's name it "Sheet1") contains the cell
(E10) which you want to check its value.

2. The second worksheet ("QBQuery1_1Criteria") contains the ranges
you are going to copy from and paste into.


Put this code  in worksheet (Sheet1) :

-----------------------------------------------------------
Private Sub Worksheet_Change(ByVal target  As Range)
If Target.Address = "$E$10" Then
With Worksheets("QBQuery1_1Criteria")
Select Case Target
Case "N/A"
.Range("O1:O530").Copy .Range("K1")
Case "All Projects Actual"
.Range("P1:P530").Copy .Range("K1")
End Select
End With
End If
End Sub
-----------------------------------------------------------


Here are my comments:

1. Change the event to (Worksheet_Change).

2. Target.Address will give the address of the changed cell, while
Target will give its value.

3. Reduce your code by using (SourceRange.Copy DestinationRange).

I did not copy your suggestion completely. I have now.
Now I am getting a Compile error as thus with the first line  of code
highlighted in the debugger:

Compile error:

Procedure declaration does not match description of event or procedure
having the same name.

Ok, I've eliminated my "Procedure declaration does not match
description of event" error with this modification to the code.

Private Sub Workbook_SheetSelectionChange(ByVal Sheet As Object, ByVal
Target As Excel.Range)
If Target = "E10" Then
Select Case Range("E10").Value
Case "N/A"
Range("QBQuery1_1Criteria!O1:O530").Select
Selection.Copy
Range("QBQuery1_1Criteria!K1").Select
ActiveSheet.Paste
Case "All Projects Actual"
Range("QBQuery1_1Criteria!P1:P530").Select
Selection.Copy
Range("QBQuery1_1Criteria!K1").Select
ActiveSheet.Paste
End Select
End If
End Sub

Problem is, I'm back where I started, nothing happens when I try to
initiate this code.

Target is a Range, comparing it with a the string "E10" only results FALSE ot
type mismatch, therefore it must be:

If Target = Range("E10") Then