DMEE EXIT MODULE

Hi,

I am doing an outbound payment file using DMEE.

i need to convert amount to amount in text (string).

we have a function module SPELL_AMOUNT.

when i select the option exit module for the element is defined and use SPELL_AMOUNT Function module. after i perform chekc it is displaying error.

could any any guide me the total process of using EXIT modules in DMEE.

Regards,

Jeff