how to get value of dictionary refrence screen field value into PAI

In module programing i have one dictionary refrence screen field - 'RF02K-LIFNR' which takes default value of vendor number while running,

problem is that how to get that value into PAI, i have defined it as data: RF02K-LIFNR LIKE RF02K-LIFNR. in PAI form - but i value is not transfered from screen to PAI.

how can we do that?

regards,

dushyant.