Cannot add ESXi Server

[ipriver]

VMware vSphere 6 Essentials Licensed for 2 physical CPUs licensed.
connectivity between machines is fine i can ping everything from everywhere and i have added the windows servers (services installed fine) however when i try to add the esxi server it returns the following.
I have tried active directory credentials domain\user as well as host\root and all return the following message


Anyone got any ideas on how i add this server i'm a first timer and it seems a little silly when connectivity is fine and the credentials are stored that it doesnt connect the windows servers were fine but the esxi doesnt want to play.
Thanks in advance

[Vitaliy S.]

Can you try to add via "root" account without "esxi\" in the beginning?

[ipriver]

I have tried this and to be fair it doesn't care what I put it's like it's not even checking because something else is the issue.
have tried domain admin account domain\user the root account and hostname\root no joy I have actually recreated the whole vm and get exactly the same.

[Gostev]

I've noticed you are trying to add ESXi 6, but vSphere 6 is not yet supported as per the sticky topic in this forum. Thanks!