Irules persistence source_addr

The problem is i want to accomplish it by Irules, this is more study case than real life, however by doing this i can learn.

The I rule i actually working as expected however changing pool and service drives me crazy i just do not understand why when i do lookup on peristent table i got value for pool "pool-http" where in fact table contains pool1-5 as show above.

So can someone advise and help me understand this behavior ?

Regards,