There are a few common reasons that an order will import in the unrecognized order status. The underlying cause is that StoreFeeder cannot find an appropriate "mapped" listing.
1. You have an unmapped listing for that channel, that links to the product ordered. To resolve in this scenario you just need to map that listing to the appropriate StoreFeeder Product. If you cannot find the listing initially remember to check your ignored listings just in case it was ignored at some point. You can do this by changing the "Controlled By StoreFeeder" column to No on the listings grid.
2. The SKU on the channel for the item ordered has changed since StoreFeeder imported the listing so StoreFeeders SKU for that product doesn't match the channel anymore. This can happen if the product was listed on the channel with the wrong SKU originally so someone has updated it on the channel but not in StoreFeeder. To Resolve this scenario you are best off finding your listing in StoreFeeder and redownloading it so it imports correctly again.
3. StoreFeeder doesn't have a copy of the listing that has been ordered. In this scenario, we'd recommend going into Settings and then pressing "Edit/View Integration" against the channel the order is for, then if you scroll down to the Stock Management Section there will be a "Download Listing Now" button (this doesn't exist for all channels. If you press that then wait a few minutes you should find your missing listing imports.
Once you have your listing mapped you just need to into the order and press update against the order line that's unrecognised or if the order was only imported recently (within the last few hours) you can delete the order so it imports again.