As others have mentioned, there are a lot of factors the Req. Worksheet is considering when making suggestions. For example, you did not mention Location on the demand (Sales Order) or the supply (Inventory and Purchase Order). We don't know the dates of the demand or supply either, which is critical in the calculation. Lastly, we don't know what criteria/filters were applied when running the Req. Worksheet calculation.
If you are using Locations (which you should, even if you only have 1), then you will either use the Manufacturing Setup > "Components at Location" (single Location only!) OR use Stockkeeping Units. The system looks at the SKU card first, and if you are planning the Item at that Location, a SKU card should exist for it. The only exception is single Location environments, where you can tell the system to use the Item Card for the planning via the "Components at Location" setting.
Your calculation start and end date are also important. Generally, you want to use today or tomorrow as your start date (can't plan the past) and an end date that is longer than the lead time of any Item captured by the calculation. You can always filter by Order Date before carrying out your plan, but if your end date didn't capture long lead demand you'll likely have a shortage or expedited shipping costs.
Troubleshooting the Req. Worksheet through the forums is challenging. I would strongly encourage you reach out to your partner for some training and review time to get started on the right path. The planning in BC is good once you dial in your settings.
Best Regards,
Ben Baxter
Accent Software Inc