about SNAT and NAT

I did a testing in my BIGIP. I created a virtual server (outbound_wildcard) and a pool (default_gateway_pool).

 

 

outbound_wildcard:

 

Destination: 0.0.0.0

 

Type: Perfomrance (Layer 4)

 

Protocol: All

 

VLAN Traffic: All VLAN

 

Default Pool: default_gateway_pool

 

Address Translation: Enabled

 

Port Translation: Enabled

 

SNAT Pool: Auto Map

 

 

**NAT List is empty**[\b]

 

 

I have setup a server and it's gateway point to my BIGIP. I tried to access the Internet from this server but not succeeded. When I unchecked Address Translation in the Virtual Server (outbound_wildcards), this server can access the Internet. Why?? In addition, why only "Standard" and "Performance (Layer 4)" have Address Translation and Port Translation option???