Validation rule is not triggering as expected.

Summary:

I am writing a validation rule on Item structures of severity "Warning". Below is the query.

Scenario 1 : I have taken an Item of class Sub assembly , "Is this SKU Physically Shipped?" == No and Item already has structure of type "BOS".

Now when I set "Is this SKU Physically Shipped?" == Yes and save the Item, the rule is triggering even though all conditions are matched.

Lets assume "Is this SKU Physically Shipped?" is still read as No. Even in that case the rule shouldn't trigger right?

Could you please help me correct the given query to validate the presence of a specific structure type based on the attribute "Is this SKU Physically Shipped?".