A NAT route is not installed in the routing table on the inside if one of the following occurs:
A maximum number of NAT policies per inside VPRN is reached. A NAT policy indirectly represents the route’s next hop in the inside routing context (toward the ISA or VM-ESA).
The next hop in the outside routing context is not available.
A maximum number of imported NAT routes is reached. There is a maximum numbers of routes that can be imported into the inside routing context from each outside VPRN.
A maximum number of the dynamic NAT routes per system is reached.