Error while trying to run a macro using a selected workbook

[simora]

I'm trying to run a macro using Application.Run from a workbook that is selected.
I'm getting an error telling me that the macro is NOT Available.
I'm using Attach = Application.GetOpenFilename to select a workbook so that I can run a macro on it.
After I have selected the workbook, I've asssigned ol as the variable for it.
I had tried using macroName but that didn't work either, so I hardCoded the Macro Name for simpicity.

Need some help with my obviously wrong syntax.

Dim macroString As String
Dim ol As Workbook
Dim macroName As String

     macroName = "MakeFinalVendors"       ' The name of the Sub procedure in the target workbook

Set ol = ActiveWorkbook  

ol.Activate
   
    ' Checking to make sure that I'm on the correct workbook
    MsgBox ActiveWorkbook.Name
    
        macroString = "'" & activeWorkbookName & "'!MakeFinalVendors'"

    ' Execute the macro
        Application.Run macroString   [  THIS IS GIVING ME  THE  ERROR ]

[June7]

Where is the code for GetOpenFilename?

Why have variable macroName then not even use it?

Where is variable activeWorkbookName declared and set?

I tested code using GetOpenFilename. The active workbook is the one with posted procedure, not the one with MakeFinalVendors.

This one-liner worked:

Sub test()
Application.Run "'" & Application.GetOpenFilename & "'!MakeFinalVendors'"
End Sub