Issue with Alternate ItemId


While creating the sales line for sales order. while selecting the Item is asking to replacing with alternate Item Id

as shown in below.



Example:Ihave taken ItemId "CNW123P-P8"  and while saving it is asking to replace  with alternative item id  "P940P-EP8".

after updating with alternate Id still it is not enabled the product dimensions fields Like SIZE, Color.

And still it is asking for site and warehouse must be filed in. both Items product Dimensions group is different.


Kindly suggest is it standard functionality or a bug.. for which items size and color will be enabled and for which items site warehouse will be enabled.