Nimbostratus
first of all, I always thought you needed to allocate an IPPortDefinition structure for the sessionState.member value before assigning it values. But, you would have got a runtime exception if that was a problem. If you are indeed getting back an error stating that the valid poolname and poolmember doesn't exist when it really does, then this is likely a product support problem.
One thing you might check is that in v11, we started a migration from the PoolMember interface back into the Pool interface. The PoolMember interface was marked deprecated and will eventually be removed. It should still work, but thought I'd bring that up. If you could try calling the LocalLB.Pool.set_member_session_enabled_state() method and seeing if that works. Info can be found here:
https://devcentral.f5.com/wiki/iControl.LocalLB__Pool__set_member_session_enabled_state.ashx
If that one works, then it's a problem with the implementation in the PoolMember.set_session_enabled_state() method.
I'll see if I can get some testing time in to try it out on my 11.1 box and see if I can reproduce.
-Joe
