Red light on hard disk one

Hi all, I have just bought a new My cloud ex 2 ultra.
I placed inside (folloqwing the instruction) the red wd 4tb hard disk. But I have a red light on the hard disk + a blue light steady on the first led above. I tried with an other one hard disk, but the problem did not changed.
Am I doing something wrong?

Hi francescosaverio88,

It seems that RAID has not been set to Auto Rebuild, and after changing the hard disk from My Cloud enclosure causes red light indication in disk LED status.
So Manual RAID rebuild must be performed in order to introduce a replacement drive and bring the RAID volume back to a “healthy” state when the RAID volume is not configured for Auto-Rebuild and one of the drives in a RAID array failed or replaced.

You may refer below article to manually Rebuild RAID on My Cloud NAS enclosure:

Thank you…Now it is ok