Field not sent by webservice deletes value of field

Hi all,

For a function module we have an existing WSDL and a few webservices.

We now have added an extra optional field to the function module and after regenerating the endpoint it shows up fine in the WSDL. The webservice however doesn't use this optional field (which is what we want). The issue is now, that eventhough the webservice doesn't send this field, it is interpreted somehow in the function module as a blank field and therefore deletes the value.

There are other fields, which the webservice doesn't send either, which are not deleted, so it does work, only not for our newly added field.

Where do we have to maintain that this perticular field is not deleted, when it is not sent at all by the webservice? (And only if the webservice sends this field and a blank value, that only then it's deleted).

Thanks!