CAD tip # 7830:

There are several possible reasons -- click on the PDF underlay to display the context ribbon and check the following:

• The PDF file exists and is properly loaded with the proper page selected (= is displayed)
• Its proper layers are on (PDF layers)
• It is not inserted in an off- or noplot-layer
• Has sufficiently high contrast and low fading (see the ribbon or Properties)
• Is not clipped
• The underlay is On (see the bulbs in the ribbon or the Properties palette)
• Switch on the PDF frame (PDFFRAME) - is it printed?
• You are using wireframe display, without hidden line removal (if you plot from a viewport, also the viewport has no HL removal settings)
• Problems displaying the PDF underlay can be caused by an incompatible graphics card
• Your printer driver or the printer itself may not be able to process complex objects (try to print to a different device or over a different driver), try to switch the PDF to a Monochrome mode