Check to make sure that you didn’t pile dirt or mulch up against the bark when you planted them.  Brush away any soil or mulch until you find the original soil that they came in.  Keep the mulchor soil away from the trunk a few inches.  Piling soil or mulch against the bark stops the flow of moisture and nutrients from the roots through the bark to the foliage above.  This is a common mistake and the main reason freshly planted shrubs and trees die.