Hi Willie,
Before clicking on the 'EXTRACT TEXT FROM FILE (OCR)' button, I'm assuming that the PDF file is easily readable on the song screen? I've tried with a few PDF files that I have and they seem to work fine, however, I only have a free SongSelect account, so can only test this with public domain songs.
If the resolution or text in the pdf is too small, the app may not be able to read it and therefore show an empty extraction. You can choose the font size for lyrics and chords in the song select screen before you download the PDF. You could try increasing this.
Gareth