Verification can fail due to various reasons. Many Pack Proof users think it's software related while it is typically not. This KB article gives an overview of the most common reasons.
Verification fails when one of the tolerances is not met. Either the paper or the ink values are not within tolerance.
Paper tolerances fail:
Check if the correct paper is loaded.
Check if the correct measurement condition is used.
Inline measurement (i1iO): always M0!
Offline measurement (ILS20/30 - SpectroProofer): is defined in the Special pane of the Property panel of the output device in the proof client.
Which is the right measurement condition?
The measurement condition (M0/M1 or M2) used for a verification should be the same as for the input profile (i.e, press profile). E.g., use M0 when using the ISOcoated_v2_eci.icc (ISO 12647-2:2007 M0 based printing standard) and use M1 when using the PSOcoated_v3.icc profile (ISO 12647-2:2013 M1 based). Note that the proofing paper should be certified for the used printing standard!
The paper tolerance is listed as "White" in the verification tool:
Ink tolerances fail:
First thing to do is check the hardware, being the printer and spectrophotometer.
Do a nozzle check and clean the print head if needed!
Verify the following when using an i1iO:
Adapt the height of the i1iO arm to the substrate (putting it too light might cause friction, putting it too high allows light entering between the i1 and substrate).
Make sure the i1iO table is leveled.
Make sure the i1 is properly placed at the feet of the i1iO arm (you will hear a click when properly placing the i1!).
Another thing to verify is the linked EPL file (which is defined on the level of the output device in the Esko Proof Client). If the wrong EPL file is used, you will get an exclamation mark next to the proofer in the device list of Color Pilot saying "The output profile has a different EPL file set!"
Ink tolerances fail because either the source / press profile doesn't fit the destination / proof profile or because the proofer is drifting (unstable printing behavior over time).
Check and recalibrate exist out of two main steps, the relinearization and recalibration steps. Relinearization is optional and will only be done when configured in the Preferences. It is recommended to only do a relinearization when the recalibration fails after at least three iterations and as a last resort before creating a new proofer profile!
When the Check and Recalibration process fails to bring the printer within tolerances it might be time to:
Create a new proofer profile You'll have to refine again the spot colors when using a new proofer profile! The spot color refinements in the exception list of the active proofing color strategy shouldn't be exchanged with the color strategy using the new proofer profile!