You completed your application for PreCheck, the faster-through-security program from the Transportation Security Administration, paid your $85, did the interview, got the OK and your flying life should be a bed of roses.

But you aren’t getting PreCheck. It doesn’t show up on your boarding pass. Here may be some reasons you’re still with the huddled masses who must remove their liquids and their laptops from their carry-ons, take off jackets and shoes and then reassemble.

>> YOU DIDN’T enter your Known Traveler Number, or KTN, when you made your airline reservation. TSA doesn’t inform the airline you have PreCheck status. You do. And you must enter your number for every airline you fly.

When you’re making your reservation, you insert your number, which may be indicated by the phrase “Trusted Traveler Number.” If you have an airline profile — that is, the airline keeps your name, email and other important information — your number may auto-populate your reservation. Make sure you double-­check in case it does not.

>> The person who bought your ticket didn’t include your number and the online airline “edit” function won’t let you input it. All is not lost. See a ticket agent at the airport and ask that it be input.

>> You mistyped your number. Create a document on which you keep important information so you can copy and paste.

>> The name on your reservation doesn’t exactly match the name under which you were approved. “Your name must be entered first, middle, last,” said Jenny Burke of the TSA. “It should match your PreCheck membership application” and be “the same in all places,” including the ID you use.

>> You know your name, but if someone else is buying your ticket, be sure that individual has spelled your name correctly.

>> You’ve used PreCheck before, but your boarding pass doesn’t include it this time. This may be a random security issue. You aren’t guaranteed PreCheck every time. Or it may be that the airline you are flying isn’t a “participating airline.” You can check TSA’s list at bit.ly/precheckairlines.

>> Or it may be that the airport you’re using is not a PreCheck airport. You can search for your airport using a TSA map at bit.ly/airportPrecheckmap.

>> You’ve broken the rules. Some infractions will earn you immediate dismissal, others a suspension. Among the most serious, Burke said, is taking a firearm through a checkpoint. PreCheck, she noted, is “not a free pass.” You can learn more about how to appeal your verdict at bit.ly/TSAappeal.

>> You arrived too early. That’s not something TSA told me; it’s something I’ve experienced at LAX when I’ve arrived at security before 5 a.m. and the PreCheck line isn’t open yet. The regular security lines are open, so if you choose to go through, just remember you’ll need to take out your liquids and your laptop, and remove your jacket and shoes.

>> You have PreCheck and you still must go through security. That is correct. Just because you have PreCheck doesn’t mean you don’t have to be screened. You do. You just don’t have to remove your shoes and liquids, etc.

IF YOU have PreCheck and it’s not being given to you, what’s the point? Why should it be that you pay your money and take your chances? Partly because it’s the nature of the security beast.

When you do get it, it’s great. TSA said the average time through security for a PreCheck member is five minutes. I won’t dispute that, based on recent experiences.

If time is of the essence, you might also consider CLEAR, which is privately run but government approved. CLEAR is a companion of, not a replacement for, PreCheck.

Here’s what happens: You show your boarding pass to the CLEAR rep, give your biometrics — fingerprints or eyes — and when you are positively identified, you get cuts in the PreCheck line.

If you decide to buy CLEAR, you’ll pay $179 a year. Certain credit cards will knock off $100. Besides airports, you also can use it to get into certain stadiums and performance venues.