Not a helpful image I'm afraid—too small to read. From what you say it sounds as if your lookup field(s) is not updating when you change SKU, and this could be due to how your relationship is set up. Suggest you post a screenshot of your Relationship graph, and/or details of the data structure.
Here is relationship.
Here is SKU lookup
I have products table and orders table. On the order form, when you select product SKU, it goes to "ProductHome" table and gets the products.
What I've done is created occurences of products and orders table. This time I linked them using "ProductDescription". What I also wanted if user select product name from dropdown, it should also populate sku code.
I'm not sure if that is causing the Issue.
It looks like you have your relationship set up wrong. You should be using ProductID_kp in the ProductHome table matching that to ProductID_kf.