I replaced 8 sheets of T-11 on the south side of my house (in Florida) a year ago before painting the entire exterior. I used Kilz latex primer and then 4 coats of Valspar Storm exterior latex. Ten months later there were dark streaks leaching thru certain areas of the new paneling (I think it was mildew, the panels were pretty green when installed). I cleaned it with a mildew remover and cleaner, let it dry out for a couple days and then painted another coat. Now, 2 months later, the same thing is happening again. Any suggestions on how to cure this problem would be greatly appreciated.