Cron Expression Does not work even if is a valid one

I want a Cron expression that catches the last working day of a month and the previous one. Like 30,31 if these 2 days are workdays.
I found:
0 0 L-1 * 1-5 which means: At 12:00 AM, 1 days before the last day of the month, Monday through Friday.
and this one:
0 0 L * 1-5 which means: At 12:00 AM, on the last day of the month, Monday through Friday.

But none of them work in Orchestrator even if i put it in this form…0 0 0 L * 2-6 *.
It is something I miss, or Orchestrator are bad at Cron expressions?

Hi @radudaniel.nica,

0 0 12 ? 1/1 SUN#4 *

Can you try this.

Regards,
MY