Code is refusing to define ranges on activesheets that are not sheet1 - excel

Question

I have a listbox on sheet1 with a list of sheetnames. When somebody double clicks on a name in the list, the code is supposed to activate that sheet, select some data and create a graph out of it.
The code is fine, right up until I ask it to define a range on the other sheet. I've had a number of different error messages and as best I can tell, the code is simply refusing to do anything that is not on sheet1. If somebody could explain why, that would be brilliant.
Code: the listbox is called Stocklist
Option Explicit
Sub StockList_DblClick(ByVal Cancel As MSForms.ReturnBoolean)
Call stockgraph
End Sub
Private Sub stockgraph()
Application.ScreenUpdating = False
Dim stockrange As Range
Dim daterange As Range
Dim security_name As String
Dim finalrow As Integer
Dim stockarray() As Double
Dim datearray() As String
Dim cell As Range
security_name = Empty
security_name = StockList.Value
If security_name = Empty Then MsgBox ("something's gone wrong, excel doesn't recognise that value") ' DEBUG
Worksheets(security_name).Activate ' --> this bit works fine
finalrow = ActiveSheet.Cells(1, 1).End(xlDown).row ' --> as does this
Set stockrange = Sheets(security_name).Range(Cells(2, 3), Cells(finalrow, 3))
' --> This gives a 1004 error, so does using activesheet
' --> if I don't reference a sheet, despite it not being the activesheet, the ranges are defined on sheet1
' --> and yet, the code was perfectly fine defining finalrow
Set daterange = Sheets(security_name).Range(Cells(2, 1), Cells(finalrow, 1))
ReDim stockarray(1 To finalrow - 1) As Double ' row 1 is a header so 2 to finalrow = 1 to finalrow-1
ReDim datearray(1 To finalrow - 1) As String
For Each cell In stockrange
stockarray(cell.row - 1) = cell.Value
Next cell
For Each cell In daterange
datearray(cell.row - 1) = cell.text
Next cell
Sheets("Top 10 holdings").Activate
' Create graph
Dim c As Chart
Dim s1 As Series
ActiveSheet.Cells(50, 50) = stockarray
ActiveSheet.Shapes.AddChart.Select
Set c = ActiveChart
Set s1 = c.SeriesCollection(1)
c.ChartType = xlLine
s1.Values = stockarray
Application.ScreenUpdating = True
End Sub

Answer 1

You cannot construct a cell range reference in that manner without fully qualifying the internal cell references used as demarcation points.
With Sheets(security_name)
finalrow = .Cells(1, 1).End(xlDown).row
Set stockrange = .Range(.Cells(2, 3), .Cells(finalrow, 3))
Set daterange = .Range(.Cells(2, 1), .Cells(finalrow, 1))
End With