pdf-to-excel file is blank ???

Your document may not contain any information that can be exported. It is for example possible that your document is a scanned document that was not OCRed (depending on what version of Acrobat you are using), or it could be because the document only contains text that was converted to outlines and therefore does no longer contain text that can be exported. Can you export to Excel from other PDF documents that come from a different source?