ImageMagick Errors: Convert PDF to Images

C:\Windows\system32>"C:\Program Files\ImageMagick-6.5.8-Q16\convert.exe" "D:\RealDocs.pptx.pdf" "d:\hello.jpg"convert.exe: `%s': %s "gswin32c.exe" -q -dQUIET -dPARANOIDSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dEPSCrop -dAlignToPixels=0 -dGridFitTT=0 "-sDEVICE=pnmraw" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-r72x72"  "-sOutputFile=C:/Users/Nupitch/AppData/Local/Temp/magick-xwOF7jbV" "-fC:/Users/Nupitch/AppData/Local/Temp/magick-BescEsek" "-fC:/Users/Nupitch/AppData/Local/Temp/magick-XfLll9WM" @ utility.c/SystemCommand/1964.convert.exe: Postscript delegate failed `D:\RealDocs.pptx.pdf': No such file ordirectory @ pdf.c/ReadPDFImage/634.convert.exe: missing an image filename `d:\hello.jpg' @ convert.c/ConvertImageCommand/2838.

谁能告诉我什么情况？