ChaRM project - landscape button gives LOGIN rfc in stead of TRUSTED rfc

I defined a project in Solution Manager. I included logical components that are Change_relevant.

I then press the System Landscape button on the Systems tab.

The system then uses for most systems the SM_XXXCLNT999_TRUSTED RFC, however, for a couple of systems RFC SM_XXXCLNT999_LOGIN is used. This means I am presented with a login screen and need to specify userid and password.

Can somebody tell me why this login RFC is used and not the trusted RFC?