Hello from JustAnswer.
To be able to say whether this would be expected would depend upon what was included in the test. A 14 panel test can contain various components, depending upon the preference of the testing program.
If the 14 panel test only contains a screening test for opiates, then it will usually fail to detect Norco, even though the Norco contains an opiate, hydrocodone. The screening test for opiates is oriented towards detecting morphine and the drugs that are metabolized into morphine, such as heroin and codeine. The hydrocodone is not metabolized into morphine, so is frequently missed by the screening test for opiates. There is a small chance for cross-reactivity, particularly if the level of hydrocodone is high, but there will be a negative screening test for opiates in most people that are taking Norco.
For Norco to be detected, it would require a screening test for hydrocodone. Or it would require that a confirmatory test be done, even if the screening test is negative. A confirmatory test, such as GC/MS (gas chromatography/mass spectrometry), will be able to detect all of the various opiates and their metabolites.
So, since you know you are taking the Norco, it is most likely that the 14 panel test only contained a screening test for opiates, and this would usually not detect the hydrocodone in the Norco.
If you have the details of which drugs were included in the 14 panel test, then I can provide more comment.