@ooctaviano
Writing DAX code needs to follow some generally accepted rules (just like in Python) so that people are able to tell at a glance whether they see a measure or a column. From your code it's not at all clear whether [Cost] and [Requested qty] are measures or columns in the table.
I'd suggest reading this guide on DAX formatting rules: Rules for DAX Code Formatting - SQLBI and sticking to them religiously.
Please bear in mind that if you iterate a fact table through an aggregator (like SUMX, for instance) you should never invoke a measure in the second argument unless you want to 1) have a model that's agonizingly slow and/or 2) produce wrong figures in a somewhat random fashion. What's worse, you won't be even able to spot the problem.
Also, I anticipate that your model is a single-table one (if not, then ignore this remark but still watch the video). If you want to see what really bad things can happen in this case, please watch this video: (1) Auto-exist on clusters or numbers - Unplugged #22 - YouTube
To be able to write a good formula for what you want, you have to show the model and also say what you want to see at the grand total.
