How to write a nant open file and replace string script

After attempting many different methods I would appreciate input.  Why does the following not work.  It does not appear to be touching the file at all.

<copy file="${makedir}\make.i" tofile="${makedir}\make.i.bak"/>                                                    
<loadfile file="${makedir}\make.i" " property="${makedir}\make.i.bak">
      <filterchain>
              <replacestring from="#old" to="new"/>
                     </filterchain>
<copy file="${makedir}\make.i.bak"  tofile="${makedir}\make.i"/>
<loadfile file="${makedir}\make.i.bak" property="${makedir}\make.i">
    </loadfile>

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