Set the lookup option for all lookup ports in the Properties window.
Lookup Name – is inherited from the associated port and cannot be changed here. To change the name of a port, select Description from the port menu.
Lookup Size – to optimize memory allocation and lookup performance, enter the estimated number of lookup records.
Lookup Empty / Null – empty and null are normally handled as “unknown” keys, thus returning the lookup default value. If empty or null values are valid keys for your lookup, you can enforce looking up the values for these keys by activating this option.