You’re using an old version of the extension, I’m pretty sure. If you have Inform 6L38 the up-to-date version of Locksmith should be included. (I’m pretty sure that the “can’t put onto something being carried rule” was eliminated from 6L38 after some discussion).
The latest version is 12 and included with the Inform installation. If you have downloaded and installed another copy it’s overriding the built-in one. Delete the one you’ve installed manually and it should work; if you’ve removed the built-in one too, re-install Inform to get a new copy.