What you've got is called silvering...
Decals require a smooth surface in order to adhere...you put the dullcote on first, which (under a microscope) creates a rough surface. The rough surface causes a diffused refraction of the light, which reduces reflection. The smoother the surface, the greater the reflection (glossiness).
The silver haze is actually an air pocket between the surface of the paint and the decal.
First thing to do, is get a new x-acto blade and make some surgical style cuts, just enough to cut through the decal film. Then coat the decal with a water and white glue mixture, and let it dry. The water will carry under the decal, the shite glue is left when the water evaporates. White gllue dries clear, and eventually fills the air pocket between the decal and surface. You may have to do this a few times. Once dry, you can clean up the surface of the decal with some warm water and a cotton swab.
Once dried, apply some Micro-set or Micro-Sol decal setting solution to the decal. This will soften the decal film and cause it to settle into any depressions under the decal. Once that's dry, apply a coat of dull-cote over the top to seal everything in.
It make take a few applications of decal solution and water and white glue to get the silvering to disappear. Best advice for the future...is FUTURE.
I build a model, and regardless of what it is, give it a coat of Future Floor wax after its painted. This gives the model a glossy surface that allows me to add decals, washes, and weathering to the model. Since Future (called Kleer in Canada) is acrylic, you don't want to put Dullcote or any enamel based clear coat over the top of it...bad things happen.
I use Tamiya X-21 Flat base mixed with Future as my Dullcote...and it works very well. If I overspray and it runs, I wash that are down with warm water and a cotton swab and respray.
Let me know if you need any additional help.
Jeff Herne
Modelwarships.com