php load image from database (pdf)

I try to upload a pdf in a site. My link works fine, the pdf file loads without problem. Right below my link I need a preview of the file as an image. There is an error with the preview, nothing shows in my boxed area. Any hinds would be appreciated.

<a href="<?php echo $pdf; ?> "PDF: ?php echo "$title"; ?> <img src="<?php echo "$pdf"; ?> " WIDTH="98%" border="1" title="<?php echo "$title"; ?> " caption="Click here to load PDF" /> </a>