Again and again, PAC do not work with CISCO VPN (OS X Mavericks)

Again and again, PAC do not work with CISCO VPN.

I have a CISCO VPN, and I set the VPN service on the top of Network Service Order, and I set a 'http://...' PAC url in the VPN proxy settings.

But when I connect the VPN, the PAC script never works.

Even when I check the access.log of the httpd server which PAC file stays, I can see there is no access to the PAC file.

I ensure the PAC script itself has no problem, If I set it in my WIFI connection proxy settings, it works well.

Anyone can Help me, or Apple thinks it is a feature not a bug?