If you can ping the IP-address without the corresponding cluster resource being online, this indicates the IP-address is allready in use by another device. Try the following commands (from the commandprompt) to retrieve the name of the device currently using the IP-address:

ping -a {ip-address}

nslookup {ip-address}

When the IP-address is currently in use (you can ping it) it will NOT be possible to bring the IP-cluster resource online. Only when the IP-address fails to be pinged you can bring the cluster resource online.

Shut down the device currently using the IP-address and then you can bring the cluster resource online.