update: problem was cause by the low hash rate of my testing machine.
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I'm setting up a p2pool for my friends to mine Litecoin.
I followed step-by-step from this post:https://bitcointalk.org/index.php?topic=62842.280
litecoind is fine, p2pool starting is fine, cgminer connection is fine.
But get this info(error) from server side:
New work for worker! Difficulty: 0.000000 Share difficulty:3.xxxx
From the cgminer side, the "diff" column is also "0".
Keep receiving
"Accepted xxxxxx Diff x/0 GPU 0"
But the total value on the top is always zero: "A:0 R:0".