It sounds like you are experiencing a paper jam with your Canon L120 fax machine when trying to print from Adobe Acrobat 3D. First, ensure that your printer is correctly connected to your computer and that the printer driver is up to date. Check the printer for any paper jams or obstructions and make sure there is enough paper in the tray. You can also try printing a test page from another program to see if the issue is specific to Adobe Acrobat 3D or if it occurs with other software as well. If the problem persists, consult the printer's user manual or contact Canon support for further assistance.