ActiveDocument.content.find.text

This question relates to the same problem as posed in my question (https://www.experts-exchange.com/questions/20329989/Collection-of-Textbox-created-from-textboxes-in-various-frames.html)

My code is as below.

The user has fields marked in the document (ie '###_fieldname_###'), I present the user with a macro in which the user can fill in textboxes, these textboxes have tags that correspond to fieldnames.

The macro I run then replaces all occurrences of the field in the document with the text associated with the textbox per the textbox.tag.

What I am trying to do is have the form run an initial check to see whether each tbox.tag exists in the document, and then to disenable the textbox accordingly.

When I run this code however it ends up with all the textboxes being grey.

***************************************************
Private sub checkform()
  dim tbox as textbox
  for each tbox in tboxCollection
    if Activedocument.Content.Find.Text = tbox.Tag Then
      tbox.Enabled = true
      tbox.BackColor = white
    Else
      tbox.Enabled = False
      tbox.BackColor = grey
    end if
  next
End Sub


**Note I have also tried a variation of the above code in which I first disenabled all the boxes, and then ran the if-then statement only enabling the appropriate boxes, not disenabling any.