Did you change the -k parameter in your bat file from groestlcoin to diamond? Caught me out at first. Mining like crazy but no accepts. Changed it and all good!

Are you sure it actually generates accepted shares? For me it does run with stratum+tcp and port 3333, but I don't get any accepted shares...
I have kernel groestlcoin in sgminer.conf.
Must I change in diamond?
Yes you should use diamond kernel.
"kernel" : "diamond"
Also if you have share difficulty 16, which is too high, use this:
"difficulty-multiplier" : "0.00390625"
Happy mining!