I'm new in your pool and just joined.
I have used the same config I use in other pool (changing server name)
But I am receiving a very high number of invalid:
10 accepted 38 stale/invalid ... it is ok ?
Have I to worry ?
Look on the CM website at your reject rate vs the pool's reject rate. If you're not drastically higher then the pool, then everything is okay. The rejected share counts displayed at the top of cgminer are often not correct on CM.