debian – Barracuda "Host access denied"

I'm trying to set up a zabbix server behind a Barracuda firewall.
Other configurations work but for some reason, this IP address is not.
"ZABBIX" on our Barracuda is a service configured as follows:

zabbix service configuration

The barracuda returns very strange messages.
One indicates that access is a "normal operation" and the second a "host access failure" (click on the image to enlarge).

80 normal operation 80 host access denied
For me, it's a very strange message because when I close my virtual machine, BC records "Host Unreachable", so the address is correct.

What could be the problem?

BTW i has disabled UFW (Uncomplicated Firewall) on my Debian (ZABBIX) computer and it still does not work.
Advices?