How to clear the batch char.tics value of MSC2N using BAPI_OBLCL_CHANGE ?

Hi ABAP ers,

I'm using BAPI_OBLCL_CHANGE in the BADI BATCH_MASTER to clear one of the batch characteristics value in classification tab of MSC2N. But If I change any other characteristics value in MSC2N they are also getting cleared without updating the new value. How to avoid clearing of other characteristics value.

Thanks,

Thilagaraj