Can we do underline,highlight and strikeout on scan document

Dear Team,
Currently i am doing underline,highlight and strikeout but it is not happening so can we do underline,highlight and strikeout on scan document

Dear apdeveloper,
This also happen with RadaeePDF's demo document?
Can you share us your document?

AddAnnotMarkup method need char index as input.
some scan image page has no any chars, and some scan image write invisible chars under the scan image(mostly it is generated by OCR engine).
the second type scan image PDF file can markup texts.

Dear Team,

Below is the attached sample PDF document in which we are able to do other annotation except Hightlight,Underline and strikeout.

The file contains a scannerized page.
No text in it, so nothing to highlight.

Also the sticky note on the page says: "This is a sample page scanned at 200dpi and converted to PDF. It is not searchable. That is, all you see is the original image of the source document."