Your post isn't clear about what you're trying to upload, but here are are few thoughts:

• Are you trying to attach a PDF to the efile of your returns?  That's on Screen 4.4, not the Import menu.
• Are you trying to import data from a PDF into Lacerte, like fixed assets or stock sales?
  • Stock sales, just enter a summary of ABCDEF into screen 17 and attach the details where you need to substantiate basis on 4.4.
  • Fixed assets, you'll have a lot easier time if you convert it to Excel.  It's a lot easier to convert your PDF through Excel>Data>Get Data>From File>PDF and find the right data.