Calculate average delay for each supplier

Hi everyone.

I've got a table that contains the name of the company's suppliers and, for each order, the expected delivery date and the confirmed delivery date.

I calculated the difference between expected and confirmed delivery date using DATEDIFF and this is what I've (correctly) got:

Now, I would like to calculate the average delay for each supplier. I tried to do it with this measure:

But the result is wrong:

They should be 0,25 days for A.D. and 2,16 for A.M.

Can you help me?