You can try again today
Please make sure to completely uninstall all old versions, remove library paths if required. Then download and install the latest version again.
ElementContainers is a new feature from quite some time ago (v3.0), meanwhile we have v3.5. Please make sure, the library path does not point to older source code or files, clean your pc of old files before installing a new version.
OK thank you
Work no.1 Thank you
My mistake
JM