Outlook - FollowHyperlink method not working

Hi all,

I have the following Excel macro which uses the FollowHyperlink method to open any saved document (.msg, .pdf, .xlsm files etc). The file names are listed in column J and the file paths in column K. This code works fine:

    Dim myFileName As String
    Dim myFilePath As String

    myFileName = Sheets("Directory 1").Range("J" & ActiveCell.Row).Value
    myFilePath = Sheets("Directory 1").Range("K" & ActiveCell.Row).Value
    
    FullName = myFilePath & "\" & myFileName

    ActiveWorkbook.FollowHyperlink FullName

What I am trying to do is replicate this macro in Outlook VBA to open documents saved to the drive based on file names and file paths listed in a multi-column ListBox. The file names are listed in the 10th column of the ListBox and the file paths in the 11th. I tried to replicate the Excel VBA code, with modifications as per below, but it doesn't work.

    Dim myFileName As String
    Dim myFilePath As String

    myFileName = ListBox1.List(ListBox1.ListIndex, 9)
    myFilePath = ListBox1.List(ListBox1.ListIndex, 10)
    
    FullName = myFilePath & "\" & myFileName

    Application.FollowHyperlink FullName

Any ideas would be much appreciated.

Many thanks