Allegro Common Lisp software problem

I've just installed the Allegro Common Lisp CL Enterprise edition. The installation manual said if run (require:build) 开发者_如何学编程with output like "fast loading.."then means the installation is successful. However,after I run

cg-user(1): (require :build),I only get "NIL".

Does that mean my installation of the software is unsuccessful?Thank you.

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No, it means that it worked ok. If there was an error, you'd end up in the debugger.

In this case, the immediate NIL response probably means the build module is already loaded into the system.