Those charts probably use a newer version of SVG (v1.1, I think), and your e-reader's software may only support the basic v1.0 without text. Hence, the green rectangles.
PDF is a nasty thing to convert properly, in any format and not just another PDF. Unless it's a tagged
PDF, you'd be better off converting the .odt into PDF. For this, use the latest version of OpenOffice, and LibreOffice (v3.4.1 and v3.6.2 right now).
since my version of Word does not have that facility I opened the document in OpenOffice
Please don't use .docx in open-source Office suits. Support was not that great the last time I tried. For .docx, use Word 2007 or newer. Adobe Acrobat integrates fine with it and comes with a 30 day trial period.