alv with method set table for first display

I'm trying to make an alv report using OO programming. I've already made it using the function module 'reuse_alv_list_display' and it's working propperly so my database query it's exactly the same, but whe I veryfy the sintax, the next error message appears:'gt_output is not type compatible with formal parameter it_outtab'. I don't know what's going on, because I think I've declared my parameters properly, anyway this is my source code:

DATA: grid TYPE REF TO cl_gui_alv_grid,

g_custom_container TYPE REF TO cl_gui_custom_container.

TYPES: BEGIN OF st_output,

tplnr LIKE viaufkst-tplnr,

pltxt LIKE iflo-pltxt,

acpos LIKE pmco-acpos,

END OF st_output.

DATA:gt_output TYPE STANDARD TABLE OF st_output WITH HEADER LINE.

SELECT-OPTIONS:TPLNR FOR gt_output-tplnr.

START-OF-SELECTION.

CALL SCREEN 1000.

*&----

*

*& Module STATUS_1000 OUTPUT

*&----

*

• text

*----

*

*creo q para hacerlo con objetos hay que definir 1º la vista, y despues

*hacer el select sobre ella, en lugar de hacer los joins en el select

*la vista que definamos se utiliza como tipo de tabla para gt_output.

MODULE STATUS_1000 OUTPUT.

• SET PF-STATUS 'xxxxxxxx'.

• SET TITLEBAR 'xxx'.

IF g_custom_container IS INITIAL.

CREATE OBJECT g_custom_container

EXPORTING

CONTAINER_NAME = 'CCCONTAINER'.

CREATE OBJECT grid

EXPORTING

I_PARENT = g_custom_container.

ENDIF.

SELECT V_{TPLNR I}PLTXT P~ACPOS

INTO CORRESPONDING FIELDS OF TABLE gt_output

FROM VIAUFKST AS V

INNER JOIN IFLO AS I

ON V_{TPLNR = I}TPLNR

INNER JOIN PMCO AS P

ON V_{OBJNR = P}OBJNR

WHERE V~TPLNR IN TPLNR.

CALL METHOD grid->set_table_for_first_display

EXPORTING I_STRUCTURE_NAME = 'st_output'

CHANGING IT_OUTTAB = gt_output.

ENDMODULE. " STATUS_1000 OUTPUT

Thanks everybody, this is a really good way to learn about ABAP programming.