Not sure what you might be doing wrong... if I use the APPLOAD command, I get the following... and then I can type CHT, and it calls the lisp as expected.
c:CHText loaded. Start command with CHT.
Change text, Version 1.02, (c) 1990-1994 by Autodesk, Inc.
Select text to change...
Do you have another lisp routine that also has CHT defined?