Getting error while using method DELETE_FIELD

Hi,

To delete certain field(s) from ALV output Im using Delete_field as follows:

DATA: LR_CMP_USAGE TYPE REF TO IF_WD_COMPONENT_USAGE,

LR_IF_CONTROLLER TYPE REF TO IWCI_SALV_WD_TABLE,

LR_VALUE TYPE REF TO CL_SALV_WD_CONFIG_TABLE,

LR_FIELD TYPE REF TO CL_SALV_WD_FIELD,

LR_AGGR_RULE TYPE REF TO CL_SALV_WD_AGGR_RULE.

LR_CMP_USAGE = WD_THIS->WD_CPUSE_ALVTEST( ).

IF LR_CMP_USAGE->HAS_ACTIVE_COMPONENT( ) IS INITIAL.

LR_CMP_USAGE->CREATE_COMPONENT( ).

ENDIF.

LR_IF_CONTROLLER = WD_THIS->WD_CPIFC_ALVTEST( ).

LR_VALUE = LR_IF_CONTROLLER->GET_MODEL( ).

CALL METHOD LR_VALUE->IF_SALV_WD_FIELD_SETTINGS~DELETE_FIELD

EXPORTING

FIELDNAME = 'AUART'.

However it is throwing me error "Method IF_SALV_WD_FIELD_SETTINGS~DELETE_FIELD of class CL_SALV_WD_CONFIG_TABLE cannot be called at this time"

Can anybody please tell me the reason and what i supposed to do to avoid it.

Rgds

Sudhanshu