Why cgminer keeps Rejecting

[kakakar]

Why cgminer keeps return lots of Rejected report, actually almost 95% are rejected. I'm playing with a Lancelot FPGA miner.
I tried combination of different version of cgminer and pools, but all the same result.
For example I used cgminer 3.1.0/3.1.1/2.10.x, pool btcguild, deepbit, even D7 pool.

Command line is like below:
cgminer -o stratum.d7.lt:8080 -u username -p password -S /dev/ttyUSB0

Cgminer Reject reports
 [2013-06-26 10:26:17] Accepted e69538a8 Diff 1/1 ICA 0
 [2013-06-26 10:26:17] Stratum from pool 0 requested work restart
 [2013-06-26 10:26:25] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T
 [2013-06-26 10:26:33] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T
 [2013-06-26 10:26:41] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T

Anyone has an idea how to fix this?

Thanks!

[kakakar]

Is there anyone in Newbie??? Obviously no one...

[mprep]

Try Tech support or Mining sub forums. Someone there might be able to help.

[aigeezer]

Is there anyone in Newbie??? Obviously no one...

You were unlucky. I'm sorry for the frustration it caused and I hope the problem got solved. People do check the newbie area for posts like yours but sometimes they get missed.

Remember to help out a newbie from time to time later on.

Thanks!
 

[JamesIV]

Not 100% sure but wouldn't the cgminer command be

cgminer -o stratum+tcp://stratum.d7.lt:8080 -u username -p password

for stratum support?

[cp1]

It says the error is duplicate share, so does that mean you're just calculating the same hash over and over again without changing it?

[Trillium]

Perhaps lowering Queue, Scan-time, Expiry parameters might be helpful. This is probably a hardware specific thing that your FPGA needs. I use the values 0 2 2 respectively for those parameters but I am not using your exact hardware. Might be worth looking into. Changing those parameters is critical for solomining many of the altcoins and even in some cases using pools.