View agent install

   I install agent(5.1) in two PCs (Win7 64, same domain, same vlan, disable firewall, open RDC, no vCenter,both virtual machine).

   but first one show first pic and next step is "installation",  and second one show the second pic（Register with View Connection Server） after "Custom Setup".

   Result, first PC can not be search by View Connection Server, the second PC can be searched cause input IP address of View Connection Server.

   Why? Is anyone could tell me?    I am totally confuse.

   Thank you in advance.