No Logon Window not reachable

Hello SAP World,

i'm facing a problem in SAP Netweaver Business Client configuration. While i'm trying to logon to the system i get the following error message:

It's in German but it means something like: "Cannot open the Logon window for this Server under the provided URL".

When i test the logon in the browser it works fine.

Any idea whats going wrong there?

Thanks for helping me out

Toby