Why Public parameter is not transfered to PERSONAL.XLSB

My workbook includes several Sheets.

Sheet1 has the table.
In the VBA item for Sheet1 I declare:
Public variable1name As String
and set a value:
variable1name = "string"

Then I call a subroutine in PERSONAL.XLSB:
Application.Run "Personal.xlsb!subroutine1"

Inside Module1 in PERSONAL.XLSB:
Sub subroutine1()
MsgBox variable1name

When I run subroutine1 from Sheet1, the MsgBox displays blank as the value of variable1name.

My question: why the value of the Public parameter variable1name is not transfered to PERSONAL.XLSB?

Thanks snb.

I tried putting the declarations
(e.g.
Public variable1name As String
Public variable2name As Integer
) in:
Module1 created under VBAProject (workbook) - it didn't work;
ThisWorkbook under VBAProject (workbook) - it didn't work;
Module1 created under VBAProject (PERSONAL.XLSB) - it didn't work.

My question is: where is the declaration area of a macro module?

Please, can anyone reply?