Greg, I must admit, I made a couple of assumptions here. Which decals (brand) is it? The one decal brand I have had an issue with, was Tabu. Though only one of theirs gave me a slight issue.
What I can add is the following. I agree 100% with what Mark has said - I also use softener and washing it off afterwards is a must. Not only will it get rid of the excess softener, but will also "test" the decal adherence before spraying it. This adds to the drying time, but so be it... Another thing this takes care of, is silvering, as Mark has said. Don't know whether you're using a softener. But what this means is it removes air trapped from under the decal, which I wonder whether this is not the cause of your issues. If there's a remote chance of ait under the decals, it will show up badly when sprayed with TS13. Also, as said previously, be very very sure the decal, it underlying adhesive and (possible) softener are bone dry.
The wet coat should also not be too thick, it will then react with the underlying layers...
There is a similar thread on F1M at this stage, so you can also have a quick look over there. maybe there's something said that triggers something with you.
Good luck!