I tested this on multiple machines and it works everywhere.
The only way I can force this error is by
- removing TMSWebCorePkgLib from the requires list of your package
AND - remove the path to TMS WEB Core "Component Library Source" folder from the IDE library path
so, I can only repeat what I already said multiple times, the DCC compiler should find units in its library path, i.e. web.pas is in the "Component Library Source" folder and when this folder is in your library path, DCC should find it.