Update cell automatically
 

Hello,

I have some code that gets the username which is as follows:

Function UserName() As String
UserName = Environ("UserName")
End Function

I call this code within a cell formula on my main sheet, the cell text is as
follows:

="Summary for " & VLOOKUP(UserName(),Sheet1!B34:C100,2,FALSE)

The workbook is a shared workbook and this works fine for me but whenever
someone else opens the workbook the cell doesnt update to their username.
However when they enter the cell in the formula bar and press enter the cell
updates.

Does anyone know how I can get the cell to update automatically?

Thanks in advance,

Martin