I solved the problem myself. I use calibre for covert html and epub in mobi, but my calibre Gui is set to my own language (not english) and It's seems that calibre assumes that all the book I convert are in the same language. This is why I can't use the english dictionary with new converted books. To solve the problem I have to edit the books metadata and set the language to english, then I can convert the book in mobi format and everything works.
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