READ THIS:

if u want to buy items:
!buy [amount] *name*
for example:
!buy 3 Non-Craftable Festivizer

Since I am not sending any messages - a couple of clarifications on why the trade failed:
Please carefully check that the price and item match when trading - the trade may be canceled if there is a mismatch between "currency and item".
Also, the trade may be canceled due to a lack of keys/metal in either inventory, Steam server issues, extra items from the buyer’s side (I do not accept items as payment), and other reasons.

If you are initiating a trade via the chat command but the trade offer does not arrive, it may be because you have insufficient funds to make the purchase, I have run out of the items you need, I cannot provide change for your keys, or there are Steam server issues.