POPUP_GET_VALUES Field is grayed out.

Hi,

I have used the FM POPUP_GET_VALUE and created my own structure and own data element the first data element for the first field is like VERPR or Moving Average Price and the Second one is like TCURR or Currency. But it seems like I cannot input any values in the first field (VERPR) can anyone help me regarding this.

DATA : ld_returncode TYPE STRING,
t_fields TYPE STANDARD TABLE OF SVAL,
wa_fields1 LIKE LINE OF t_fields,
wa_fields2 LIKE LINE OF t_fields.

wa_fields1-tabname = 'ZVALCURTAB'.

wa_fields1-fieldname = 'ZVALUE'. "Data Element Like VERPR this is grayed out.
wa_fields1-field_obl = 'X'.
wa_fields1-value = '5000'.
append wa_fields1 to t_fields.

wa_fields2-tabname = 'ZVALCURTAB'.
wa_fields2-fieldname = 'ZCURRENCY'.

wa_fields2-field_obl = 'X'.
wa_fields2-value = 'USD'.
append wa_fields2 to t_fields.

CALL FUNCTION 'POPUP_GET_VALUES'
EXPORTING
popup_title = 'Enter Local Capital Threshold Criteria'
start_column = 5
start_row = 5
IMPORTING
returncode = ld_returncode
TABLES
fields = t_fields
EXCEPTIONS
ERROR_IN_FIELDS = 1
. " POPUP_GET_VALUES

IF SY-SUBRC EQ 0.
"All OK
ENDIF.