Is your document a scanned document or a bitmap image of text the size of a page? If so, please OCR your document. OCR is the process of converting a bitmap image of text (like a scanned document) into text that can be selected, copied, and searched.
You can automatically OCR as well as manually OCR the document. You can set your OCR preferences in PDFpen > Preferences. Or, you can manually OCR the document if the program does not automatically recognize the document as a large bitmap image of text the size of a page/ scanned document as well. You can find more information on OCR here: