Okay fellas. I found the answer.Here it is.

The supposed Request URI to retrieve contacts related to a contact group is like this: https://www.google.com/m8/feeds/contacts/default/full?&group=http://www.google.com/m8/feeds/groups/yourmail%40gmail.com/base/xxxxxxx

where xxxxxx is the contact group id.

Before this I'm using this Request URI : https://www.google.com/m8/feeds/contacts/default/full?&group=xxxxxxx

where xxxxxx is the contact group id and the result is will be failed because I'm just put the group id instead of use full uri of contacts group .

So that's all.Hope its help.