I can't highlight/mark text in my pdf-dokument using Adobe Reader on my iPad. I can highlight text in the same dokument if I open it in Adobe Reader on my computer.
What to do?.
In general, you should be able to select text and add text markup annotations (Highlight, Underline, and Strikethrough) to a PDF document in Acrobat Reader for iPhone and iPad except the following cases.
(a) Your PDF document is a scanned document that contains no actual text.
You need to convert text images to editable text using OCR (Optical Character Recognition) technology.
(b) Your PDF document is encrypted. Acrobat Reader for iPhone and iPad does not support saving changes to encrypted PDF documents. This is a limitation in Acrobat Reader mobile apps for iOS, Android, and Windows Phone.
(c) Your PDF document disallows commenting due to document restrictions.
Do you see the lock icon in the bottom bar when you open your PDF document in Acrobat Reader for iPhone and iPad? If so, your case is (b). Because you can add Highlight to the document in the desktop version of Acrobat Reader.
Please let us know if you would like us to examine your PDF document and determine the exact cause of the problem.
Sorry for the inconvenience.