Loop Until Reference = Error

I'm trying to create a simply loop for an easy task of copying and then pasting a formula into other cells. Basically I'm trying to get this script to run until there is no more "slsperson" references to go to.


Sub z_Paste_Sales_Formula()
Dim i As Long
Dim icolumn As Integer
icolumn = 4
Cells(3, icolumn).Select
Selection.Copy
i = 1
Do
Application.Goto Reference:="slsperson" & i
ActiveCell.Offset(1, 0).Select
sls_row = ActiveCell.Row
ActiveCell.Offset(1, 0).Select
gp_row = ActiveCell.Row
Cells(sls_row, icolumn).Select
ActiveSheet.Paste
Number = i + 1
Loop Until Application.Goto Reference:="slsperson" & number = error
End Sub