CAD tip # 12131:

This may have several causes - from the most frequent:

1. A missing call to the function loading the "VLAX" support for accessing the ActiveX programming interface - i.e. (vl-load-com) - try to type it on the AutoCAD command line and retry your LISP program.
2. You are trying to run your LISP program in AutoCAD for Mac - but this version doesn't support the Windows-specific (ActiveX) VLAX functions.
3. A damaged or missing or antivirus-blocked file adding the VL-functions, i.e. VL.ARX - should be in the folder C:\Program Files\Autodesk\AutoCAD 20XX\
4. A missing reference to the class type library. Check these Registry settings using the Regedit application (replace "XX" and "##" with the version available in your AutoCAD folder - e.g. "vl16.tlb"):

   [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{A4081F53-974E-479E-A26E-E6DE9A5B2489}]
   
   [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{A4081F53-974E-479E-A26E-E6DE9A5B2489}\1.0]
   @="Visual Lisp ActiveX module"
   
   [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{A4081F53-974E-479E-A26E-E6DE9A5B2489}\1.0\0]
   
   [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{A4081F53-974E-479E-A26E-E6DE9A5B2489}\1.0\0\win32]
   @="vl##.tlb"
   
   [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{A4081F53-974E-479E-A26E-E6DE9A5B2489}\1.0\0\win64]
   @="C:\\Program Files\\Autodesk\\AutoCAD 20XX\\vl##.tlb"