There could be a number of causes. You haven't given us any information
about your situation, so I can guess, but that's what it is. I mean no
'preaching', but let me outline some of the areas where a 'problem' could
Industry standards for epublications have a basic level of features that
all ebook publishers and distributors will meet. Some will go farther than
others, and some will have proprietary features that will restrict the way
that ebooks are used. Amazon is the most visible of these, linking its
Kindle ereaders to their website by using proprietary coding in their
The ebook itself is prepared by the publisher, and is supposed to be done
to the basic standard for the industry, so every one's ereader or computer
software will display it properly. However, they may add some features
that go beyond the basics, which allow certain ereaders to do additional
things, like varying the text size and reformatting pages when displayed if
those features are built into the ereader software.
The software you use to move and display the ebook also should be working
according to the industry standard. However, as with any software, there
are levels of that standard, and not all ebook display software will
display all features.
Ereaders themselves also should be able to display the text of an ebook
according to the standards, but all of them seem to have different
'features' that may not work 'according to standard'. This is particularly
true of the lower level of ereaders coming from China and being sold here
with an odd name.
The industry is morphing all the time, and new devices such as tablets come
out with software that says it will let you read ebooks, but doesn't tell
you how to do that.
So, I don't know what type of device you're using to read ebooks, but I
assume from your comments that it says it will read the basic industry
standard ebooks. However, from what you've said, I'll guess that either
the ereader or the software that you use on the erader (tablet, for
example) doesn't support some of the features that are embedded in the text
of the ebook - or isn't working correctly with the 'standard industry
text'. This could be the fault of the ereader or the publisher who
composed the ebook.
If you repost and give us more information about your ereader, maybe we can
be a bit more specific.