CTRL+ALT+DEL does not work when using UltraVNC

1) „Start menu” -> „Execute” – > gpedit.msc
2) Navigate to „Computer Configuration” -> „Administrative Templates” -> „Windows Components” -> „Windows Logon Options”
3) Double-click on the „Disable or enable software Secure Attention Sequence” parameter.
4) Check „Enable”, then select „Services” in the combobox.
5) Apply the modification