Pfsense proxy server , wan static ip configuration doesn't work.

[lwinlay]

hello pls help,, i use pfsense proxy server with ADSL internet line. When i put the static ip in the wan port, it doesn't work.
So i test and change with another ISP which give DHCP auto configure to wan port. It work & client can access internet.
So pls, why static ip configuration don't work in pfsense proxy server.If there is another another additional problem , pls help me how to fix this.