There are 4 seals on each injector. 2 are o-rings and the other 2 are bushings. Pull everything out again. Make sure that you replace at least all of the o-rings and put a dab of WD40 on each of the top ones before you put them back into the rail.

Normally, I push each injector into the rail just far enough for them to be held in. Next, align each injector with the appropriate hole on the intake manifold. Gently push the rail down so that the injectors slide into the holes. Make sure to apply even pressure along the entire rail. Now, take a rubber mallet and gently tap the rail several times above each injector. Finally, put the bolts back in the rail and tighten.