Problems with connect to a share on a cluster 2008 with ip address

Hello,

I have built a new Cluster 2008 an copied solle Files via robocopy to the new cluster. Now I have the following problem.

Connect via \\IP-address\share --> does not work
Connect via \\servername\share --> does work

Has somebody an idea what this could be?

Cluster: 2 nodes, activ, activ

Connect via \\ip-address\c$ --> does work

Greetz
QuentinT