Monitoring Websphere Network Deployment problems

Hello,
I have some problems to monitor a WebSphere Network Deployment installation with global security activated.
I was able to create a monitor for Websphere, but it always states that 'Resource is down', regardless of the real state of Websphere.
Trying to add a custom attribute, the error 'java.lang.NoClassDefFoundError: com/ibm/jsse/IBMJSSEProvider' is displayed.
System is:
- AIX with WebSphere Network Deployment 5.1.1.6 and I also tried
- AIX with WebSphere Network Deployment 5.0.2.4

Application Manager is build 6020 (still trial version) and runs on a windows workstation.
No firewalls are involved.
Any help would be appreciated.