did you prime first?was the wood damp or wet or was the humidity high?did you put on multiple coats or too heavy before drying?Was the wood green or not all the way dried?
Then the main part is "box store".
I would try again, but forget the box store. Sand the deck, make sure the wood is completely dry. Prime that sucker, and apply several coats of light coats of paint. allowing to dry after each coat.
Use paint from only a paint dealer.
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