Unable to do so convert UOM rate of an Item has two Primary UOMs in different organizations.

I am calling an package which fetches the Item ID (inventory_item_id), Secondary UOM (secondary_uom_code), Primary UOM (primary_uom_code), Conversion rate (1/ unit_weight) and sends these values as input parameters to an Standard API

inv_convert.create_uom_conversion ();

-->     The program runs and the standard API which is called inside the program throws an error showing “Unexpected error occurred”.

-->     I assume the issue is because, the Item has two Primary UOMs in different organizations.

-->   There is no exception as far as i see(correct me if i am wrong) "too_many_rows" in the standard API.