Here below you may find valuable info on Text Extraction Troubleshooting.
There exist 3 main issues you may experience:
1. Notification Baloon is displayed and Plagiarism Detector denies plagiarism check:
"Error Code Diagnostics"
Details here: http://www.plagiarism-detector.com/smf_bb/index.php/topic,37.0.html
2. Check is completed Ok, but the extracted text is not complete (some parts are missing):
"Incomplete Text Extraction issue"
Details here: http://www.plagiarism-detector.com/smf_bb/index.php/topic,37.0.html
3. The Originality Report displays lots of question marks instead of text or unreadable symbols:
"Wrong encoding issue"
Details here: http://www.plagiarism-detector.com/smf_bb/index.php/topic,36.msg37.html#msg37