Error Message 'Subscript Out of Range'

Hi all -

See if you can see what is wrong with this code - I have no idea. All the spreadsheet names are correct and I have used this syntax before, I don't know what I am doing wrong. The macro has a problem with the 3rd line (

Sheets("Data").Range("a3").Activate

), here is the code:

Sub Hiwhatsup()
Workbooks.Open Filename:="S:\PROJECTS\Traffic\Revisions\Test Spreadsheet #3.xls"
Sheets("Data").Range("a3").Activate
Range("a3").Activate
Range("a3:o5000").Select
Selection.Copy
Windows("Test Spreadsheet #4.xls").Activate
Range("a5").Activate
Selection.Paste
Application.CutCopyMode = False
End Sub

Thanks for your help.