irule to replace source IP with an arbitrary IP

Ok. I am trying a simple code as shown below. When the snat command is commented out, the virtual server that is loaded with the irule forwards the packet. When I uncomment out the snat statement, the virtual server does not forward the packet that matches the source IP w.x.y.z though the log statements show in /var/log/ltm file.

 

I am using bigIP version LTM 9.4.4 HF3.

 

What am I doing wrong?

 

 

when CLIENT_ACCEPTED {

 

if {[IP::addr [IP::client_addr] equals w.x.y.z]} {

 

log local0. "before snat"

 

snat m.n.o.p

 

log local0. "after snat"

 

}

 

if {[UDP::payload] contains "_avcv_"} {

 

log local0. "in UDP payload"

 

node a.b.c.d 5060

 

}

 

}