Is it possible that there is a 4 character minimum word length for searching. On vb4 I believe that is the default. I think I had to set mine to three -- to catch industrial acronyms used on the board I run,
I ran the word 'box' on here and it did not catch that either. I doubt that box and CMS are in the reserved word list, but banning three character words is quite common.
I could be all wrong so don't take my word for it