Can not use 'AT LINE-SELECTION' with SET PF-STATUS

Hi experts,

my code is like below:

PARAMATERS: .....

SET PF-STATUS 'st_nam'.

Perform Load_data . ' For list display

START-OF-SELECTION.

AT LINE-SELECTION.

Perform list_detail.

AT USER-COMMAND.

CALL SCREEN '1001'.

END-OF-SELECTION.

When I execute the report , the basic was displayed , but when then i double click on the list to call the next screen '1001'. It did not work , but if i omit the SET PF-STATUS m AT LINE-SELECTION worked week , so in this case what has happened i how can i solve this problem,

Thaks,

PS: Reward immediately