My hazmat one-time fee is not being factored into price when added to cart

[tcarden]

I've set up an Attribute with a One-Time charge but it is not being factored into the price. like it's being dropped once in the Cart but it does show on the product page.

Here's how I have it set up:

The purpose is to flag a product as HazMat so a one time shipping charge of $25 can be added. Attribute is set up w/ one value only. Once assigned to the product, a value of $25 is set in the 'One Time' field. Attribute flags include 'Default Attributes to be Marked Selected'. I've tried setting 'Used For Display Purposes Only:' to both Yes and then No but doesn't change the outcome.

Here's a screensnap to help show how i've set. Can anyone say what i'm doing wrong here?

big thanks in advance