BAPI_PO_CREATE1 EXTENSIOIN

Hi:

I'm trying to create a purchase order via BAPI_PO_CREATE1 with EXTENSIONIN informed. I need to fill customer specific fields, but these fields appears empty.

data begin of x_extensionin occurs 0.

include structure bapiparex.

data end of x_extensionin.

move 'BAPI_TE_MEPOACCOUNTING' to x_extensionin-structure.

move '......' to x_extensionin-valuepart1.

append x_extensionin.

Thanks in advance.

Abel