I want to second Americar’s suggestion. Was your car thoroughly warmed up at the time of the test? One example of many: My brother took a '90’s Corolla in for an emissions test which it didn’t pass. On advice, he took it for a drive on the freeway and got it warmed up and then it passed the test by a healthy margin. Several friends have had similar experiences. A warmed up engine can make a difference–I always make sure my pre-OBDII cars are plenty warmed up before getting them inspected.
When you’re waiting in line at the emissions test station, DON’T shut off the engine. The engine will cool, and the car may not pass the test. If you’re next to be tested, turn on the a/c, or anything to put a load on the engine, to keep it warm. You could, even, put it in gear (foot on brake, of course) and raise the engine rpm to about 1500 for a few minuets. Otherwise, you may have to take the car out for a drive to reset certain things in the computer.