You have to wait for the Sol and Set to set and dry properly, you also have to brush off gently with a Q-tip the set and sol once its on the decal, if you leave it floating or drenched in the stuff it won't settle down and once you apply any varnish over them they'll peel.
Another thing, get the Tamiya Gloss I've found that some enamel varnishes can eat away at the decals causing them to peel. Also apply any gloss your sparying in light coats, You don't want the plane looking like its been drenched in water.
There are too many reasons why the decal could of peeled and silvered, the only thing that matters is fixing it
.
I've never had issues with Eduard decals, but I'll repeat that Future is amazing stuff and you should let it dry at least 2 days inbetween applications so for example
Apply future to the painted model, wait 2 days,
apply decals, wait 1 day to dry,
apply future wait 2 days to dry,
apply flat clear wait 1 day to dry, done
Hope that helped, the reason why the decals were destroyed is simply, either over watered with gloss, solution (sol, set) or they havn't been given enough time to dry between the set of applications of themselves and varnish.
Igor
P.S. If you want to thin Future to give it a less gloss look thin it with water (it sounds crazy but it works
) don't thin it with thinner it won't work that well. Because you use the thinner itself (or anything that contains ammonia) to remove future from the surface of the model) I've even used Tamiya acry. Thinner to remove future and its worked fine for me on models, but Windex is still the lax when it comes to removing Future.
One more thing, apply Future as Airframes stated, with a brush to whatever entire surface (to keep a uniform gloss) to the model. If you apply it with a air brush you can clog it, and you'll end up cleaning it all night and through the morning :S