It would appear that you're using a newer Infinispan client against an older Infinispan server.
This newer Infinispan client uses, by default, the more efficient version of the Hot Rod protocol 1.1. Whereas the server you have probably does not understand this.
If you want your client to stick to 1.0 (which I don't recommend), pass infinispan.client.hotrod.protocol_version property to the RemoteCacheManager with "1.0" in it.
Otherwise, simply upgrade your server to 5.1.2.FINAL.
You are right, I have two versions of infinispan 5.0.1 and 5.1.2, by mistake,i started startserver.bat from 5.0.1