How can I record Ntempo ?

[Zblogny]

Hello,
My first attempt to add a Ntempo staff in a score is unsuccessful.
I have created a Ntempo staff, filled it with notes everywhere I need them, press the T button in transport bar, press the perform button. I can see NTempo staff blue-highlighted. I press a key in the proper range of computer keyboard, the score plays following my keystrokes. When it reaches the end, I cant see any balls and lines mark as should be expected.
What am I forgetting to do ?
Thanks