Multiple SNAT pools under a single VIP

Hi Folks, 

I need some help on having two SNAT pools under a single VIP. We have a VIP that contains 4 nodes present at two different locations (2 nodes in A location and other 2 nodes in B location), having different subnets (we have separate routes to reach each location). What we want to achieve here is to have two different SNAT pools under a single VIP, each dedicated for each subnet.

let us say, I have 2 nodes under subnet 10.0.0.0/24 and 2 nodes under 20.0.0.0/24 such that traffic uses SNAT POOLs used: SNAT-1-->members--> 11.1.1.1 & 11.1.1.2 to reach nodes 10.0.0.0/24. SNAT-2-->members--> 12.1.1.1 & 12.1.1.2 to reach nodes 20.0.0.0/24.

I'm using the following irule but it throws errors. error 1. missing an expression, error 2. undefined procedure,

when LB_SELECTED {
  if { [IP::addr [LB::server addr] equals 10.0.0.0/24] } {
    snatpool snat-1
  } else if { [IP::addr [LB::server addr] equals 10.0.0.0/24] } {
      snatpool snat-2
  }
}

Please help to achive the requirement.