well & is missing just in this last post, normaly I have it.
But it seems I have found the problem, and as I thought it is the way you write it:
so instead of
=[par_id] & ", " & [par_name] & ", " & IIf(IsNull([par_name]), "", [par_name])
you have to write
=[par_id] & ", " & [par_name] & "...