Samsung portable ssd T5

I've just bought a Samsung portable ssd T5 and tried to connect to my iMac mid 2011, running High Sierra. The message is that this disk can not be read and gives the options: Format, Ignore or eject. I asked for format and did so through Disk Utility, which recognizes the disk but defines partition and S.M.A.R.T. as incompatible. I tried to erase for many times, in all possible formats, and always get the message that the process failed, cause it was not possible to record in the last block of the device. I also tried the Samsung software to get to mount the disk but did not work. Could anyone help me? The disk seems to be working… when I run repair it is ok but I don't have any other option. thank you!!!