Set clearing restriction 8 in instalment line items

Hello,

We want to set clearing restriction 8 in the instalment line items through a custom program, which are already created in past. Certain line items of instalments are open and we want to set restriction 8 in the open line items however we are not able to set restriction in already created instalment line items.

We tried to use FKK_DB_DFKKOP_AUGRS_SET function module to set restriction 8 but system is not allowing to set restriction.

Thanks & Regards,

Narendra