Noob Question: Hide

[Diaz Ex Machina]

How can I hide/preclude all the other traits that don't come from a determined source? Like, if I have "The Shackled City" source selected I want to see only its traits, nothing else (not even - Custom Trait -).
I've tried this method, but it gives me this error:

Here's the code I used (Phase First, Priority 10000, Index 1):

      ~ Find all other traits
      foreach thing in Trait where "!TraitCat.ShackCity"

        ~ If no trait category then pull the thingid
        If (eachthing.tagcount[TraitCat.?] = 0) Then
          perform eachthing.pulltags[thingid.?,HideTrait]
        ~ If we have a category then pull the cateogry only
        ~ if we have not already pulled it.
        Else
          If (eachthing.intersect[TraitCat,TraitCat] = 0) then
            perform eachthing.pulltags[TraitCat.?]
          Endif
        Endif
      nexteach

      ~ Create Hide Trait Catagory tags
      perform pulltags[TraitCat.?,HideTrCat]
      ~ Push the hide trait tags to the hero
      perform hero.pushtags[HideTrCat.?]
      perform hero.pushtags[HideTrait.?]

Thank you in advance for your help and time.