persitence entry lookup across two different VS

This is a tough one because of the way your are doing persistence. Have you read this article and made certain it does not apply to you?

https://support.f5.com/kb/en-us/solutions/public/9000/800/sol9815.html

I also found:

http://devcentral.f5.com/wiki/default.aspx/iRules/persist.html

Is it possible that since there are multiple pools involved with your persistence that you have to set the values and use "any pool" like this:

when HTTP_REQUEST {
    Save the value of the UIE persistence record for this client for any pool
   set value [persist lookup uie "[IP::client_addr] any pool"]
}