In AutoCAD,
vlax-import-type-library is
executed at runtime rather than at compiletime. The following
practices are recommended when using vlax-import-type-library:
If you want your code to run on different machines, avoid
specifying an absolute path in the tlb-filename parameter.
If possible, avoid using vlax-import-type-library from
inside any AutoLISP expression (in other words, always call it from
a top-level position).
In your AutoLISP source file, code the vlax-import-type-library call
before any code that uses method or property wrappers or constants
defined in the type library.