SM59: Remote Log on: nothing happens

We have the problem to access remote a SAP system from another SAP system (SOLMAN) via SM 59 --> Remote Logon.

Following was allready done:

- the same user is exist on both system

- the appropriate user in SM59 has S_RFCACL object

- the settings in SMT1 and SMT2 are ok

Question:

What can be the error here?

Any helpful information will be very appreciated!