Hi again, first of all i dont think you should have nulls on your records, please take some time and read this topic:
Nulls: Should it ever be meaningful?
http://www.access-programmers.co.uk/forums/showthread.php?t=131571
If you don't want to show where the nulls are just add to the filter "fldName is Not Null" (if you have more than one criteria go for example like this "fld2Name > 0 AND fldName is Not Null)
I know lol, the small arrow is cool. To create that effect u can create a bmp (bitmap Image) on paint very little like 4x4 pixels, one pointing upwards and another pointing downwards and put them next to the label of the field (imgAscendant, imgDecendant). Then on Label Click (lblfldName) event do something like this.
Sub lblfldName_Click()
If Me.OrderBy = "fldName" Then
Me.Orderby = "fldName Desc"
Me.imgAscendant.Visible = False
Me.imgDecendant.Visible = True
Else
Me.Orderby = "fldName"
Me.imgAscendant.Visible = True
Me.imgDecendant.Visible = False
End If
End Sub