O.K. it is not such serious Problem.
However it is the first time that i am very happy that i can add a second miner.
I have 8 GB and 4 GB cards so i can mine ETC at the 8GB and ETH on the 4GB cards without taking the 4GB out an put them in another rack. Thank you for that!
However as i was playing arround i add a third miner and i could not see this miner by pressing CTRL a+a+a. Did i miss something?