field unknow error in enhancement

Hi Experts,

Am implementing one enhancement in standart function module.

ENHANCEMENT 1 Z_ENHANCEMENT_CASE. "active version

CASE ISEGM-SEGNAM.

WHEN 'Z1SDEXT'.

v_flag_sdext = 1.

WHEN C_Z1BPTRANNO.

v_flag_tranno = 1.

v_z1bptranno = ISEGM-SDATA.

v_transferno = v_z1bptranno-zz_transfer_no.

ENDCASE.

ENDENHANCEMENT.

Variable declaration in top.

ENHANCEMENT 1 Z_ENHANCEMENT_TOP. "active version

DATA: v_transferno type ekko-zz_transfer_no,

v_z1bptranno type z1bptranno,

v_flag_sdext(1) type c,

v_flag_tranno(1) type c.

DATA: c_z1sdext like edidd-segnam value 'Z1SDEXT',

c_z1bptranno like edidd-segnam value 'Z1BPTRANNO'.

ENDENHANCEMENT.

$$-End: (1)----

---

$$

while checking for syntax it showing error as "Field "V_FLAG_SDEXT" is unknown. It is neither in one of the specified tables nor defined by a DATA statement". When i

click on the field it is taking me to the top where i have declared the field in enhancement. What is the problem.

Thanks & Regards

Sridevi S