[WWI] Airbrushing Clear Flat

[mikemuth at ptd.net]

I have run into this problem 2 times recently. I had decided to apply a gloss
coat before applying decals. I used a spray can Gloss from Model Master. I let
the plane sit for more than 3 days. I then tried to airbursh Clear Flat
Lacquer from the MM bottle. The look was great, but it appeared to have some
small, white flecks that were left. The airbrush had been cleaned before I
started. The second time, on a different model, I again used the spray can,
but this time I let the model sit for a week. Then I cut the clear flat with
the appropriate thinner. Fewer white fl;ecks,  but they were still there.
Anyone got any ideas? Not enough thinner? Too much? Gloss from the can doesn't
mix with the flat from the bottle? I don't think it is the airbrush as I had
cleaned it beforehand both times.
TIA
Mike Muth