Hi,
Sorry but from the image I don't see nothing wrong.
I see two options one on the KMS server check the Event Viewer you will have a category there with all the activation request and if you compare the requests you can discover which failed and the name of the client affected and also some error code. The error code will not always help some times the error generated on the client side, if you use slmgr.vbs to activate, can give more clues about the problem. Usually searching the client error in google gives more tips to solve the problem...