newbie question re 'pool' command

I'm trying to use the following snippet in an irule

when HTTP_RESPONSE_DATA {
  pool tp_web_svrs_80 member 10.10.10.39 80
  HTTP::retry $original_request
}

but the request is being sent to the default pool (tp_red_svrs_80) on the vip instead of to the tp_web_svrs_80 pool member (10.10.10.39).

The tp_web_svrs_80 pool member is up.

The $original_request is a properly formed and complete GET request.

If I set the vip default pool to tp_web_svrs_80 the request works but it breaks what the rest of the irule is trying to achieve.

This is on LTM version 10.2.0.

Am I using the pool command correctly?

Am I using the HTTP::retry command correctly?

Thanks,

Jeff