Customer Exit For Variables

Hi Experts,

I am getting an error while using a varible created by customer exit.

The Requirement is that when the user entered the date value in the 0CALDAY,it will display the

data from the 1st date of the month to the date entered in the selection.(single entry)

I am using the field 0CALDAY on which created a variable ZCMTD1(by customer exit).

when running the report,it is displaying only the value of the same date.

Please any body can check and give me the idea so that i can proceed.

i have written the below codes....

DATA: L_S_RANGE TYPE RSR_S_RANGESID.

CASE I_VNAM.

WHEN 'ZCMTD'.

data: ZCMTD_LOW like sy-datum.

ZCMTD_LOW = sy-datum.

ZCMTD_LOW+6(2) = '01'.

CLEAR L_S_RANGE.

L_S_RANGE-LOW = ZCMTD_LOW.

L_S_RANGE-HIGH = SY-DATUM.

L_S_RANGE-SIGN = 'I'.

L_S_RANGE-OPT = 'BT'.

APPEND L_S_RANGE TO E_T_RANGE.

IF I_STEP = 1.

RAISE NO_PROCESSING.

ENDIF.

ENDCASE.

Regards

Debasish