Problem with website on NLB Servers to access the Active Directory

[Brave]

Hello,

I have sometimes the problem to get information from Active Directory
(100 times it works without any problems but the next time I had the problem.)
If I copy the Web-application on the single server It works without any
problem.
The problem is definitely a cluster problem.
(On each IIS itself it works, but when I go over the cluster-IP I get
sometimes the error.

How can I solve this Problem?

Bye Brave