Formula for Selling Price - Cost, only if Sold

Hi,

I've been trying to do this for the past hour with no luck so hopefully someone on here can help me

What I want to do is in Minus the cost of a product (Column D) from the selling price of the same product (Column C) only if SOLD is written in Column E, and then have the total of this in Column F.

I've tried SUMIF which seems to be the right formula but no matter what I do it doesn't seem to work.

If anyone could advise me on what to do I would be very grateful. Any other information you need please let me know

Thanks,