SAP Logon Groups

We are trying to build up a new infrastructure with the mySAP ERP Release. We successfully did a migration from sun/Oracle to Windows2003 as Application Servers and z/OS/DB2 V8 as Database Server. Unfortunately the login from SAP GUI doesen'work. I get this error message:

Error Serice sapmsSSW not found.

We checked a lot of things like the rdisp/mshost and rdisp/msserv, but it still doesn't work.

We have 2 applications Servers.

Thanks for your help