Export and import data between 2 screen of same program thorugh field exit

Hi.

I have requirement  to export and import data between 2 screen of same program, Actually I have T.code FI01  in this When I entered Bank key e.g 23 it moves to the next screen. I want to display the bank name on to the next screen  corresponding to bank key, let suppose bank key 23  which have bank name  'national bank' must be displayed to the next screen field of bank name, I am using field exit to tackle this problem, first I am using bank key fierld which have data element of  BANKK   OF FIELD= BNKA-BANKL,

Code of bank key field is this.

FUNCTION FIELD_EXIT_BANKK_1.
*"----------------------------------------------------------------------
*"*"Local Interface:
*"  IMPORTING
*"     REFERENCE(INPUT)
*"  EXPORTING
*"     REFERENCE(OUTPUT)
*"----------------------------------------------------------------------
DATA: BANK_DETAIL  LIKE  BNKA_BF.


if sy-Tcode = 'FI01'.

Data it-bank type BNKA-BANKL.
it-bank = input.
export it-bank from it-bank to MEMORY id 'MY ID'.

ENDIF.
  ENDFUNCTION

First Screen:-

Field Exit of Bank name.which is on next screen,

Actually I importing the bank key into this field exit so on the basis of this i would get the accurate value of corresponding bank  name to display automatically on bank name screen, but it not importing the field actually.

FUNCTION FIELD_EXIT_BANKA.
*"----------------------------------------------------------------------
*"*"Local Interface:
*"  IMPORTING
*"     REFERENCE(INPUT)
*"  EXPORTING
*"     REFERENCE(OUTPUT)
*"----------------------------------------------------------------------

Data it-bank type BNKA-BANKA.
import it-bank = it-bank from MEMORY id ' MY ID '.

IT-BANK = IT-BANK.

ENDFUNCTION.

Next screen :-

Kindly help me in this regard as I am new to sap abap

Thanks