Please note that offers from us may be sent to Steam Accounts that meet certain conditions (according to the Steam Terms of Service). The trade offer may not be proceeded when:
- The account was created less than 15 days earlier
- Steam Guard is not added to the account
- Steam Guard has been disabled
- Steam Guard has been reset
- Your account password has been reset
More information on exchange restrictions can be found here: https://help.steampowered.com/en/faqs/view/451E-96B3-D194-50FC#pwreset
You can check why trading is not possible on your account by clicking Community and selecting Market from the menu. If the trade is not possible, Steam will show the reasons in the table at the top of the page, along with the date when the trade will be again possible for your account.