table control from internal table giving problem.

HI ALL,

I am creating a table control using wizard from internal table in the program when i give work area it gives this error "The table work area G_TABC_WA does not exist or is not a structure"

I have declared internal table and work like this.

TYPES: BEGIN OF T_TABC,

OPTID LIKE ZHRPMT_TRNSAC-OPTID,

STGID LIKE ZHRPMT_TRNSAC-STGID,

TETID LIKE ZHRPMT_TRNSAC-TETID,

REQSR LIKE ZHRPMT_TRNSAC-REQSR,

MUNIT LIKE ZHRPMT_TRNSAC-MUNIT,

END OF T_TABC.

DATA: G_TABC_ITAB TYPE T_TABC OCCURS 0,

G_TABC_WA TYPE T_TABC. "work area

why it is giving this error and how to correct this.

thanks.