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zkab - if you do want further help regarding calibre conversions you will have to frame the request as per this - which is a Sticky at the top of this subforum ==>>
How to ask a question about conversion problems
I use calibre to convert upwards of a dozen DOCX's a day to EPUB, many of them originate as PDF's. But if the document has many tables, sidebars, images etc etc - I leave it as PDF. If you want to read the PDF on a small screen (phone, tablet) then have a look at Willus' pdf optimiser, it's in the PDF forum.
If you have access to Word (2007 and up) you could try Toxaris' EpubTools addin - it's in the Workshop forum.
BR