Why is there an error accepting this trade offer?

If you get the classic "There was an error accepting this trade offer. Please try again later", this error is because of an issue with your steam client. A quick restart should solve the problem. There was an error accepting this trade offer. Please try again later. (8)

Why do I still get the error (28) when all items are present?

If you still have the error when all items are present then it's a server side issue and it should just fix itsself after awhile. Hope this helps. I get the error (28) once in a while. Just keep clicking until it goes through, usually works. Clicking doesnt help in my case.

What can I not include in a trade or trade offer?

Any tradable items in your inventory. Note that you cannot include Steam Wallet funds in a trade or trade offer. If someone sends you a trade offer claiming to include Steam Wallet funds it may be a scam. You can report scammers using the "Report Violation" link on their profile.

How do I accept the trade in offer?

On the trade in page you will need to tick the box indicating that you accept them. If you don't want to accept, you will not be able to receive the Trade In discount. How does the offer work? You can trade in any one of the following devices online, in-store or by calling our agents (“Trade In Devices” or “old device”):