: The LISP routine was never loaded into the active drawing, or you opened a new drawing window without putting the file in the Startup Suite.
Autodesk now offers an “AutoLISP Download” section. autocad tlenlsp download work
Traditionally, LT versions did not support LISP routines. However, AutoCAD LT 2024 and newer now include AutoLISP support, meaning you can finally use TLEN.lsp in LT. : The LISP routine was never loaded into