On Mon, 13 Aug 2012 13:05:54 -0700 (PDT), DerbyDad03
wrote:

I'm guessing that the repair wasn't feathered out far enough to blend
in with the rest of the wall. Build it up high and feather it down
onto the existing wall.

If the OP is just using sand paper / drywall sanding screen in his
hand it will not be flat. A small block of wood will go a long way to
prevent improper sanding; instead just using paper in hand.
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