error message: you have specified appears to be already assigned to another system on the network wh

when I deinstalled 11.1.0.7 crs from the unrInstaller and tried to re-install i got this message.

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The virtual hostname(s), sso-ata10-v,sso-ata12-v, you have specified appears to be already assigned to another system on the network.  Please ensure that the virtual hostname(s) that you use for each of the nodes in the cluster are not in use currently.

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whe I ping  sso-ata10-v
PING sso-ata10-v (10.252.35.16) 56(84) bytes of data.
64 bytes from sso-ata10-v (10.252.35.16): icmp_seq=0 ttl=64 time=0.063 ms
64 bytes from sso-ata10-v (10.252.35.16): icmp_seq=1 ttl=64 time=0.055 ms
64 bytes from sso-ata10-v (10.252.35.16): icmp_seq=2 ttl=64 time=0.022 ms
64 bytes from sso-ata10-v (10.252.35.16): icmp_seq=3 ttl=64 time=0.055 ms