Windows("file name always different").Activate cant reference the workbook in my MACRO !!

All
My macro is not working and im at a loss

I have 2 workbooks “FORM” and “EXPORT MASTER” and essentially FORM is for entering data and EXPORT MASTER is for collecting it
Unfortunately because all users need to print FORM and get a signature on it before sending it on to a different department to then bring the data back up using the unique reference number that’s created this is the only way it can be done and explaining the ins and outs of the 20 departments it affects would take me a long time so your gonna have to trust me theres no way around it.


When users have completed all information in FORM and start the macro then FORM is saved as a new filename which changes every time (and is taken from Cell AV36) using the below code……

'Save form as filename CRN+AMOUNT
    If ActiveSheet.Range("AW30") = 0 Then
    SAVENAME1 = ActiveSheet.Range("AV36")
    SAVENAME2 = "S:\Finance\Financial Operations\CHQ REQ\PAYREQs\" & SAVENAME1
    ActiveWorkbook.SaveAs Filename:=SAVENAME2
    
    Else
    If ActiveSheet.Range("AW30") > 0 Then
    Exit Sub


End If
End If

Then EXPORT MASTER workbook is activated and a unique reference number created which is then copied…….

'  OPEN MASTER SHEET
    Workbooks.Open Filename:= _
        "S:\Finance\Financial Operations\CHQ REQ\EXPORT MASTER.xls"
        
    Windows("EXPORT MASTER.xls").Activate
    Range("A1").Select
    Selection.End(xlDown).Select
    ActiveCell.Offset(1, 0).Range("A1").Select
    ActiveCell.FormulaR1C1 = "=R[-1]C+1"
    ActiveCell.Select
    Selection.Copy

This is where my problem occurs…..

Windows("SAVENAME2").Activate
    Range("U2:X2").Select
    ActiveSheet.Paste

As I try to refer back to FORM under its new filename I do not know how to refer to it correctly so I can paste the unique number back
I have tried many different versions of
Windows("SAVENAME2").Activate
But none seem to work

After I have got back to it then the rest of the macro worsk fine…

' COPY DATA LINE TO MASTERWORKBOOK

    Sheets("UPLOAD LINE").Select
    Rows("4:5").Select
    Application.CutCopyMode = False
    Selection.Copy
    Windows("EXPORT MASTER.xls").Activate
    Selection.PasteSpecial Paste:=xlPasteValuesAndNumberFormats, Operation:= _
        xlNone, SkipBlanks:=False, Transpose:=False
    Range("A1").Select
    
' SAVE AND CLOSE

    ActiveWorkbook.Save
    ActiveWindow.Close
    Sheets("FORM").Select
    Range("A1").Select
    
    
End Sub

I wish to add more but will not complicate the macro any further until ive fixed this part

Many thanks in advance for your help 

Michael