Numbering ON/OFF assigend to short cut key ctrl+shift+N does not work [closed]

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I want to use the short cut key ctrl+shift+N to switch Numbering ON/OFF. However, nothing happens when doing ctrl+shift+N

I did:

Click Toolbar / Customize click tab Keyboard click into Shortcut key window to ctrl+shift+N => nothing was assigned select Catagory: Numbering select Command: Numbering ON/OFF click Modify => Numbering ON/OFF is assigned to ctrl+shift+N

do ctrl+shift+N nothing happens but do ctrl+shift+B works and starts / stops a bullet list

close LibO and restart => no difference

Why is ctrl+shift+ B (bullet list on/off) working and ctrl+shift+N (numbering on/off) is not working?

Thanks I advance for help!

LibO4.0.4.2 / XP