AdvancedFilter Error 1004 - works in one Excel 2003 workbook but not another

Hi,

I'm new to VBA so generally put together any macros I need by searching forums for other people with similar problems / recording a macro and customising.

I've got a pretty basic macro I'm using to create unique lists which I want to use for drop-downs. I have to work in Excel 2003 unfortunately as the users don't have anything newer.

This macro works with absolutely no problems in an otherwise empty Excel 2003 test workbook, but when I use it in the main workbook where I actually need it, I get a 1004 error, saying the advanced filter method of the range object couldn't run (Have to back-translate from German there, so that may not be the precise English wording).

Sub Unique_Filter()
'
' Unique_Filter Macro
'

Application.ScreenUpdating = False


'Create unique list


Sheets("Database").Select
With Sheets("Database")
    Range("C1", "C65000").AdvancedFilter Action:=xlFilterCopy, copytorange:=Sheets("AuxList").Range("B5"), Unique:=True
   
End With

Sheets("AuxList").Select
Application.ScreenUpdating = True


End Sub

What settings in Excel 2003 could be preventing this from working in one workbook when it works fine in another?

Thanks in advance for anyone with any ideas about what could be causing this!