Changing value of select-options according to list box value select

Hi all,

I have a requirement ..... i hav a list box and select-option. when ever user will select a value from (parameter) list box the correspoding value from a z-table should be set and should get displayed in the select-option . The select-options get set in initialization but the list box values are populated in at selection-screen output .....

So How can i do this ? Thanks in advance..