Forfiles command not working with autoit

So Im trying to use FORFILES dos command with autoit.  Here is the command

Forfiles /P C:\users /M *.txt /C "cmd /c ReplaceText @path yes no /I"

Basically this will look at every .txt file in the C:\users directory and replace the word YES with the word NO using replacetext.vbs

I can type this into a command window and it works great.  However it does not work with autoit.

Here is a simple command.

Run(@ComSpec & " /c " & "FORFILES /P C:\Users")

That command should show you a list of every file in the C:\users directory,  But I cannot get it to work.  If I type into a command window, it works.

Any help would be apreciated