DNAT doesn't work when changing the destination port

I am trying to publish a web console. With below settings, it works fine:

NAT Rule

Rule Type : DNAT

Matching Condition

For traffic from : Any

Using Service : TCP 80

Going to : External (WAN)

Action

Change the destination to : [My Web Service]

Automatic firewall rule : Yes

Once I changed to below, it doesn't work anymore

NAT Rule

Rule Type : DNAT

Matching Condition

For traffic from : Any

Using Service : TCP 8888

Going to : External (WAN)

Action

Change the destination to : [My Web Service]

And the service to : TCP 80

Automatic firewall rule : Yes