OK. I've found the answer.
If anyone got the same problem as me, you may have to try uncheck the option "Only scan my computer (no-promiscuous)."
I'm not sure it's a right way or not; however, it works under my situation.
So eventually my URL Snooper can sniff network packets correctly now.

BTW, sometimes we must try and try by ourself. Relying on others usually can't get what we really want.

Hi,

I've installed the newest version of URL Snooper (2.26.01) and WinPcap (4.1.1) in my computer, and when I started it, it said that Auto Detect is failed.
Okay, then I selected the adapter driver manually, in my list is "Network adapter 'Realtek PCIe GBE Family Controller' on localhost."
However, when I clicked the "Sniff Network" and try to sniff something, it doesn't work.
No any URL show up in list and no packets be accouted in status bar.
I executed URL Snooper under Admin right, and My firewall is NIS 2010, but I've set a rule that let both URL Snooper and WinPcap access network.

I executed windump with -D parameter and got this information:

D:\>windump.exe -D
1.\Device\NPF_{4CF18BD9-EE19-4BE6-8932-9B4FAA3222D8} (Realtek PCIe GBE Family Controller)

My OS is Windows 7 Ultimate x64，MB is Gigabyte MA770T-UD3P, and the on-board Network Contrller is Realtek RTL8168C/8111C PCI-E Gigabit Ethernet Adapter (PHY: Realtek RTL8211/8212) PCI.

Are those information enough to report and solve the problem? ;)