I transferred $72.74 in BTC to my account here and immediately traded for 40 each TF2 keys at $1.69 each. The trade offer only sent 30. Please look into this matter. I have purchased many keys here with BTC over the years and have never encountered this. Thank you.

You have made an bid order of 40 keys at $1.69 each, but there were only 30 of them selling at that price, your order was only partially filled and the remaining 10 keys are still on the order book, waiting for someone to sell at $1.69 or lower.

You had only paid for 30 keys and your remaining credit are locked for that 10 keys bid.