SUMIF (OR SUMIFS) Using data from named ranges in dynamic drop down list

Hi Pepe,

Thanks. I built a new, simplified sheet to try and illustrate what I'm looking to accomplish.

The cells highlighted in yellow are what I currently have. I can run the formula to add the quantity and extension of any particular order, if I enter the 'order number' into the appropriate field ('1880' is entered in the example).

What i want to do, is get use the drop-down list i've created (highlighted in red), where i can choose the headings and values and have the formula automatically update. I hope i've explained this correctly!