ActiveVBProject.References Error in .FullPath

We have a module that checks machine information for troubleshooting. One of the helper modules checks each link for breaks. However, for one reference, Microsoft Office Soap Library 3.0 stops at an error.

We can work around this, but I'm really curious to know what is causing this error. The link is valid, not broken. The referenced object method just fails for this library.

Failed to execute method 'FullPath' of object 'Reference'

Private Sub getEachRef()

Dim ref As Variant
Dim strRef As String

'On Error Resume Next <- this allows the rest of the code to complete

For Each ref In Application.VBE.ActiveVBProject.References

    frmAbout.lst_About.AddItem "[Reference] " & ref.Description
    frmAbout.lst_About.List(frmAbout.lst_About.ListCount - 1, 1) = ref.FullPath <- error is here

    If ref.IsBroken = True Then
        frmAbout.lst_About.List(frmAbout.lst_About.ListCount - 1, 2) = "Broken Link"
    End If

Next

End Sub