Split text (More Tag) doesn’t work with multiple authors

Hi
My weblog (http://blog.karaloka.net) has 9 authors, but only my account (administrator) can split all the texts, despite all of us have the button “split” or “more”. The status of others is set like this: “author”. I don’t want to change them to “editor” or “administrator”. Why this status (author) can’t split its own texts? This bug is so boring…
Thank’s.
Regards
Yuri
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http://karaloka.net