Applescript - replace text in specific text frame

Question

Throwing another one out there to is excellent forum:
I know how to change text in a document:
tell application "Adobe InDesign CS5.5"
          set find text preferences to nothing
          set change text preferences to nothing
  --Search the document for the string.
          set find what of find text preferences to "SigBelowT"
  --Replace the search with what we pulled from the db
          set change to of change text preferences to theSigCopyB
  -- this is the actual search and replace command
          set myFoundItems to change text
end tell
I'm trying to change text only in a specific paragraph, named as a layer in my source inDesign Document:
tell application "Adobe InDesign CS5.5"
          tell the active document
                    try
                              set find text preferences to nothing
                              set change text preferences to nothing
                              set Text_Frame to the text frame "PH"
                              set find what of find text preferences to "~" of text frame Text_Frame
                              set change to of change text preferences to " "
                              set myFoundItems to change text
                    end try
          end tell
end tell
I've tried several iterations similiar to this one, but I'm not hitting the right combination.
Suggestions??

Answer 1

headed down this path:
tell application "Adobe InDesign CS5.5"
          try
                    set myDoc to active document
                    set Text_Frame to the text frame "PH"
                    set find text preferences to nothing
                    set change text preferences to nothing
                    set find what of find text preferences to "~"
                    set change to of change text preferences to " "
                    tell myDoc
                              tell Text_Frame
                                        set myFoundItems to change text
                              end tell
                    end tell
          end try
end tell
still not working