You've got the right colour paint (and a good quality one) but it is not going to exactly match old faded paint, which is what is on the trailer. The CARC paint on military vehicles is known for fading, especially the black, which turns to a bluey-grey.
Rapco paints also need time to cure. They go on a little dark, and often with a bit of shine to them, but in about a week (depending on the weather/indoors-outdoors, etc) it will settle to the correct shade and sheen.
If you look at military trucks that have been in service long enough to get retouched here and there, they will have a blotchy appearance from mismatched paint fade.
Cheers
