TouchUp Text Tool

I am able to use the "TouchUp Text Tool" on some .pdf's with text,
but not others. I printed a page from the web, I was able to:
 
Highlight text with the TouchUp Tool, delete any text I wanted, even add text.
(I thought this was cool).
 
So then, I went to my office's (employer) web site and downloaded a few .pdf
text documents that we use as our contracts. I was unable to get the TouchUp Tool to
work.
 
I went to: Documents>OCR Text Recognition>Recognize Text Using OCR...
After that, I was able to "highlight" but Still unable to "Edit Text"
 
Any advise would help...
 
Like I said, I can use this function on some pdf's but not on my contracts...
 
bradwallace
Southern Illinois