STOCK_BIN Table Access_group can not be patched

Hi there,

I have a problem which I dont really understand.

I tery updating the Access_group in the Stock_bin Table over a Business Rule but the System ignores just the Access_Group.

All other Date ist patched correctly except this.

Is this a normal behaviour? 

My XML Call ist like this:

<update_stock_bin>
  <stock_bin>
    <bin_id>LOCATION</bin_id>
    <condition_code>New</condition_code>
    <location>GOOD</location>
    <part_id>Part</part_id>
    <place_id>TESTSTOCK</place_id>
    <usable>Y</usable>
    <access_group>ACCESS</access_group>
    <insert_update is_initialized="False" />
  </stock_bin>
</update_stock_bin>

Can someone please help?

Thanks in advance