Cash journal splitting problems

Dear experts,

I can't understand cash journal splitting principles and how does it work. Because documentation in help.sap.com is very poor about this.

I have entered one line item in FBCJ, and then press on "Split" button. System shows me splitting screen and there I see my just entered line item with all my account assignements. I don't want to add more line items for splitting, so I press on the button "Copy". And nothing heapens!!! After document posting to general ledger I don't see (in document General Ledger view) account assignements to Cash Journal line item... (!!!)

What I am doing wrong?