PDF header signature not found.
   at iTextSharp.text.pdf.PdfReader..ctor(IRandomAccessSource byteSource, Boolean partialRead, Byte[] ownerPassword, X509Certificate certificate, ICipherParameters certificateKey, Boolean closeSourceOnConstructorError)
   at iTextSharp.text.pdf.PdfReader..ctor(Byte[] pdfIn)
   at AutoDCR.Signing2.ClassFiles.AddBoxesInPDF.AddBoxes(String sSrcFilePath, String sDstFilePath, Int64 ProposalID, Int32 CertiType, String sSealImagePath, Int64 piMessageID, Int32 piDocumentID, Int32 designationId, Int32 iRecordID)