Help PLS T_T replace activity

For replace activity (words) why do I have a error on the left hand side (search for) ?
The error is replace activity value cannot be null parameter not valid.
I only keyed in ‘’<. Name of People. >`` in the search for which is exactly the same words found in my word doc
The right hand side(Replace) I put my variable in
The work I did was
Word application scope > replace activity
I’m not sure if I need to have read text activity as well but if I put it in there was an error for the read text activity because the file is already open in the word application scope