If steam is banning your account, it's most likely for a good reason, but if you feel like you're being abused, then you should bring it up with Steam Support.

What are you trading?

Yep, everything other than untradable achievement items will become tradable after going premium.

Have you tried this solution?

https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/558747922562007365/#c540742485388491621

This bug has already been addressed, in your case, you can either type out the full name, or the game has never been entered into the database.

https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/617328415067970704/
https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/540743757114639301/

Nope,

http://www.tf2outpost.com/rules
https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/46476691260571979/

Confused as to what you're asking, but it seems like you're asking for a set to be traded to you.

In that case, trading is prohibited on the forums, please take a closer gander at the rules,
https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/558755530343215312/

See if this helps,
https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/558747922562007365/#c540742485388491621

Originally posted by harsheldon:

I was banned for trading with Ethika. no trades with Nieroda have occured since his mark, and i havent been banned for trading with Nieroda.

They must of added it on as extra proof,
Either way, the rules don't bend because he's your friend or gives you the items for free, trading with a marked user is a bannable offense as stated in the rules.

If you're still concerned, create a ticket.

http://i.gyazo.com/6cfaafa9dc64178da704421391b519ab.png http://i.gyazo.com/cedc564cd86306e5e1d16749dad613dc.png